I think it's also worth looking into non-Linux operating systems.
ReactOS is supposed to be able to run Windows programs as well as Windows does, while being separate enough that it doesn't contain any Windows code and Microsoft can't do anything about it. I tried to install it last time i had a spare computer but i couldn't get it to work†. I don't remember why. Anyway, dual booting that could be good for gaming and anything that can't be done with Linux programs.
I've been on Linux long enough that i only miss Windows supporting 90% of programs when i'm trying to do something like get games to recognize a controller that's not an Xbox controller, or i'm struggling to think of any other examples. Now i actually have more trouble getting things to work when i'm trying to help my brother with tech problems on his Windows11 computer. (Why does it keep trying to put everything in OneDrive folders instead of local storage⸮ Why are the file manager and notepad trying to look like web browsers⸮ Why can't i just see what's in a folder without it organizing everything weirdly⸮)
I'd also like to add that if you're considering using a particular distro, places like that distro's support forum might be good for seeing what problems you should expect to face. Dedicated forum sites, Stackexchange, Reddit, etc.
Here's one for Linux Mint.
The big thing for me is gaming. I never touched Linux before because of its lacking support for many games. However! This has changed in recent time! Thanks to Steam, a lot of my games work on Linux now! Only thing I'd worry about are my non-Steam games, but tbh, I probably won't play them much. (For Fortnite, I'll just play on Console. For Valorant, I won't play it because I only played it for college esports lol.)
I've been using Linux Mint* for a couple years now and i don't have too many problems with most games i play. For games that don't officially support Linux and aren't on Steam, i think you can still add them to your library as non-Steam games to use Proton, Steam's version of Wine. Or if you don't like that you could try to set up Wine yourself, but i've had trouble with that†.
Proton works pretty well for every Steam game i've played with it, but most of the games i play have Linux builds so i don't usually need it.
Another note about Steam, i use an unofficial AppImage build rather than the official Linux release because that lets me keep almost all of Steam's files contained in a single folder that fits within my organization structure. I can try to find a link to that if anyone's curious. It still updates and runs fine (as long as you don't put it in a folder with a space in its name) and i haven't noticed any problems with it at all, except maybe it takes a little longer to start up sometimes. Which is not an issue if you're someone who lets Steam start up automatically every time you start your computer.
Customization isn't too hard. I use a custom cursor set made from one someone made for Windows, and it's not too hard to make and use new icons for file types and stuff. I'm pretty sure you can make a whole custom theme with icons for all the system buttons.
Actually I did put Linux Mint on a USB a few days ago and booted it, but it worked horribly slow.
It's been a while since i last reinstalled Linux and had cause to run it like that, but i'm pretty sure that's just because it's running from a USB stick. My last computer had about 30GB storage (and half of that was just Windows for a long time, then i switch to Linux and that took only a third) so i ran almost everything from an external drive (an SD card, then a USB stick, then a bigger hard drive) and it was very slow.
* A couple years ago i restarted my computer and Windows refused to boot. I looked up what the easiest to use Linux distro was and that's what i found. It works well enough that i still use it now.
† But i think i might just be particularly bad at that sort of thing, since i tend to avoid learning stuff about computers until right when i need that knowledge.