I’m not a GNU/Linux expert, I’ve only used it on a server for a short time, but I have some things to share.

Remember: search engines are your best friend! Obviously it would be better for someone to recommend a program for your specific use case, but you can find things like notepadqq (Notepad++) or xone (Drivers for your Xbox One controllers) with just one search.

About GNU/Linux distributions: each of them provide a different set of software, including package manager, desktop environment, file system, etc. You can basically ignore the differences between distros if you use distrobox, which will let you install software regardless of your distro. Other differences will mainly be in the actual software they distribute (so you may need to use sudo apt rather than pacman or whatever.

The “flavours” of distros can mean different things, often though they just have a different desktop environment so it runs kinda different, or it is designed for a different use case.

For your use case, Pop!_OS has an ISO that includes Nvidia drivers, and Linux Mint also lets you install the proprietary drivers. Both are fairly common in the GNU/Linux space (especially with beginners) so you can get tons of support with those.

I know in GrapheneOS that the Google Play Services are sandboxed and you can install them in a specific user profile, but I’m not sure if doing that still gives you notifications across those profiles

Hopefully someone with a little more knowledge of this can help? lol

It might be a good substitute for some. Some features like contact and storage scopes are missing, and IMO they’re pretty cool Overall just worse privacy and security compared to Graphene

By default, sure. But uBlock is way more powerful when you configure it. Seriously, take a look at their wiki. I doubt that Brave lets you choose exactly which domains to connect to on a per-site basis. And do you really want an advertising company to make your adblocker? They’ve done shadier stuff.