It's somewhat SoC dependent, but the actual feature support depends on auxiliary chips. Of the well-supported phones, only the Shift6mq supports it in hardware - software support on mainline is not there yet though. The Fairphones 4 and 5 also have the feature. I have the 5, and display out works with postmarketOS, but audio support is still lacking, and USB peripherals (e.g., keyboard, mouse) are not supported.

Here's a list of more devices: https://www.uperfectmonitor.com/pages/list-of-smartphones-with-displayport-alt-mode

That said, there are other ways like DisplayLink and or GUD that may enable you to connect a display to a OnePlus 6 or PocoF1 anyway, some people have done it (and left video evidence on social media or YouTube. It definitely requires a customized kernel, and unfortunately, AFAIK the efforts have not been documented/shared (kernel config and necessary packages).

[–] dingdongitsabear@lemmy.ml 2 points 5 months ago

thank you for the elaborate write-up. all them models listed are either way out of my budget, don't support pmOS or are shitty (4 GB RAM, etc). searching GSMArena for 'displayport' nets also 50ish models, all cream of the crop type of deal; I was hoping I'd score a cheap ex-flagship and get myself a nice workstation for experimentation.

in the meantime I've gotten myself a Poco F1 for cheap, I'm now awaiting the week-long bootloader unlock timer to expire and I'll try to use it as a phone only.