Android

What about an external, optical camera lens ? I would 100% pay for a phone that looks like a brick but that has an optical zoom

Modular everything. I really wanted Project Ara to come to market.

• Removable battery
• Ambidextrous button placement
• Screws instead of glue where possible
• USB4 + desktop mode

Max 4 inch screen, IR blaster, physical keyboard with speed dial settings for buttons, form factor like the Xperia x10 mini pro, headphone jack, cameraless, LED with customisable lights for different notifications, bonus - built in projector, satellite phone capability,

Really would love a dedicated camera button that acts as a soft shutter release. Or a button in that position that's programmable.

More phones like the Fairphone/Framework Laptop. Easy to repair and upgrade in a modular manner, as well as install what ever OS I choose.

Larger, swappable battery. Squeeze for assistant

I want a phone with an ultrasonic fingerprint reader, those are apparently a niche feature nowadays. The optical readers are terrible by comparison.

Ability to use the screen as a display through the USB port so I can debug a lot of my systems at home without needing to carry a monitor around.

I'm on a Fold 4 now and I do love the novelty/oddity aspect of having a folding tablet.

But I would love to see the return of IR blasters on most phones and sliding phones for physical keyboards.

Plastic back and a removable/user replaceable battery.

Yeah yeah I know it "feels cheap" but honestly I LIKED when phones were made of more plastic. Now they're heavier and both sides are breakable. Like, the metal backs were fine, but apparently metal backs suck for NFC and wireless charging so instead of giving us some classy Nokia Lumia style plastic they went with glass backs.

Also I keep my phone in a case because otherwise the back is so smooth it shoots off the couch if someone walks across my apartment. It's legit only in the case to add some friction.

Phone upgrades.
Battery.. Non lithuim. Flexible and new. []
Flexible screen. Wrist strap or just flexible. []
Fitness/health capabilities. []
Usb 3.1 reversible.. Proper specs [x]
Wireless charging. Using new WiFi microwave to charge phone without mat. Wattup []
Better nfc/Google pay [x]
Smaller screen oled,s than 5.5 []
Better speakers none conduction or ceramic
Encryption []
Bezelless. Screen to screen hole cut out. 2018 []
Solar panel in screen. Sapphire glass. Smudge and germ

This list was created a few years ago.

Some things have been implemented but not all.

Slide out controller, like the Xperia Play. I've gotten super into (at least the idea of) SBC handheld gaming, and there's just nothing quite like the Xperia Play now. Sure, there's bluetooth controllers, but I'm not a big fan of bluetooth, and the majority of the bluetooth controllers make portability a pain rather than it being a sleek package.

Better system font/typeface selection and a way to install new ones. I know it's a petty gripe, but the default android options are few and terrible.

Hackability

Native Bluetooth GPS support. I do mapping for OpenStreetMap a lot and the built in GPS modules are just too bad for that. Currently I have to use an app to get my Bluetooth GPS connected. But sometimes this app fails and the built in GPS takes over and ruins my logs.

I just want a new Droid with a slide-out keyboard

I've had every one of them until the Droid 4 and they never released a new one

Today my wish is for an internal pihole instance running on the device.

Officially supported rooting! Makes this less complicated.

Niche feature....

By Apple's standards a headphone jack.

By Android's standards IR blaster. Had them in my last 2 phone and man is it nice to turn the volume down on a TV which is too loud in a public place like a Hotel Lobby or a Restaurant

A full physical QWERTY keypad on my 3rd hand Blackberry Bold (in 2013) was the best thing I had seen on a cell phone. I wish full physical QWERTY keyboards would make a comeback.

A swappable battery. I could buy a few batteries and never be out of power. I could replace the battery on an older phone without pretty much having to replace the phone itself.

This is going to be such a stretch and I doubt this would ever happen, but if you could get a decently sized camera sensor on the back of a phone and a mirror less style lens mount...I would sell my DLSR in a heartbeat.

true background process management and battery

A phone built somewhat like a desktop PC. All parts replaceable or even upgradable. Choose the components for your needs and budget, or buy a pre-built.
But let's get to more standard smartphone concept.
On software side, no bootloader locks, or easily unlockable bootloader (not requiring internet) and root access that could be enabled in developer settings.

On hardware side:
IR blaster - Control your AC, TV, etc.
Front-facing stereo speakers - could give a better stereo sound. And bezels aren't a big problem. Actually they can be positive as you can hold your phone better with them.
Headphone jack - Obvious. Would be cool if it had mode for composite output, but that's quite extra.
Dedicated fingerprint scanner on front - I had this on Moto G5s Plus. It allowed awesome gesture navigation, much better than using whatever on-screen.
Trackpoint - Early Androids used to have that. Would definitely be useful with large screens.
FM, HD Radio, DAB, DAB+, DVB-T2 Lite receiver - Radio is pretty useful. AM would also be nice, though you would need external antenna better than cable from earphones. I think FM radio is the minimum here.
TV Receiver - Just like with radio, except now you're saving much more on mobile data.
Camera with optical zoom - We've been there with Samsung in the past. But I understand it makes things too large and heavy.
Projector - We've been there with Samsung in the past, again. I think it was done pretty nicely on the projector part with Beam 2. It didn't even add much thickness. Just the rest of the phone was meh.

Foldable display - They are still way too expensive!

Metal case - I just loved the heavy Samsung Omnia 7 metal case. It made it unbreakable and grippy!

A Silent/Vibrate/Ring switch like on the OnePlus phones, headphone jack and a easily swappable battery.

duck duck go tracker blocking that doesn't use vpn technology

Does the alert slider counts as a niche feature? Very few brands provides this.

Keyboard. I want a damn keyboard. I'm a blackberry refugee hiding out on a unihertz titan/titan slim

i'm certain this is going to be a just me thing but i'm a nostalgic fool and would love a notch in the casing to put a lanyard/phone strap. that, and a physical keyboard. if you could get modern android and a good camera in the form factor of the original motorola razr i'd be so happy lol

IR Blaster, Headphonejack, SD Card Slot, removable battery