A lot of programs I work with very often are Windows-exclusive, and alternatives supporting Linux are rare.
Consider mentioning the programs you work with. On a general note, Wine can be used to make Windows-software work on Linux. Bottles can be used to that effect as a front-end. Furthermore, for a more sophisticated solution; consider taking a look at CodeWeavers.
Unfortunately, good affordable hardware on which Linux is properly supported is hard to get by. I'm personally fond of vendors like (in alphabetical order) Framework, NovaCustom, Star Labs, System76, Tuxedo. But other vendors like ASUS, Dell, HP and Lenovo are known to sell devices that do a considerable job at supporting Linux; consider to check the compatibility/support for their devices through resources like linux-hardware.org.
Regarding video types; I don't think you should have any problems regarding those; on some distros it might not be supported by default, but that should be solvable with a single command. Relying on flatpaks^[1]^ instead is another viable solution and is enabled by default on a lot of distros. Moving on to word document templates; I suppose the suite of cloud-based services found in Microsoft 365 should work regardless. As for the question if the templates would work on LibreOffice, ONLYOFFICE and the like; I simply don't know. On to familiarity of OS and using it for business purposes; most distros that are friendlier towards newer users have been setup with sane defaults. Therefore, I don't think there's a lot that could go wrong as long as you're interacting with a GUI. When interacting with a command-line interface, note that information found on the internet is often times outdated. Therefore, if you're hesitant or unsure; consider interacting with the community for some help. We're all in this together!
You should be totally fine aside from some software that's known to not support Linux at all.
Ask yourself the following questions:
Somewhat related to the previous question*. Like, there are distros out there that I can install for my grandfather and he wouldn't even notice the difference. But even some (relatively) mainstream-distros can be daunting for so-called power users of Windows. E.g. I would argue I was your average Windows-user; play games, browse the internet, email, write documents, video-editing, run software required for my studies etc. It took me about two weeks before I was 'comfortable' on Linux. And even then, some of the software I used for e.g. video-editing just didn't want to play nice^[2]^.
If you want freedom and control over your devices, there's simply no viable alternative.
Software management on Linux -at least on the surface- is closer to Android/iOS than to Windows. You should rarely (if at all) feel the need to find software through your browser. Instead, you should interact with so-called package managers. This can be achieved through either a command-line interface or a storefront with a GUI that behaves like those found on Android/iOS etc. Coming back to Flatpak; this is an (upcoming) universal (read: (mostly) distro-agnostic) package manager that tries to solve a lot of problems that traditional package managers have had. There's still a lot of ongoing work for it to achieve its design-goals to the fullest, but even in its current iteration it works excellent and therefore it's unsurprising to find it enabled by default on a significant chunk of the Linux landscape. Software that are packaged using this technology are referred to as flatpaks (or flatpak if singular).
In retrospect, this seems to be primarily rooted in the fact that my machine isn't that powerful in the first place. On Windows, it managed because it was better optimized for it. Unfortunately, on Linux, this was not the case.