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.

The desktop client logs and sends lists of currently running processes by default, and they also collect usage data (which channels you open, how long for, who you’re interacting with). In the settings, there’s literally an option for “Use data to customize my Discord experience”. And sure, they don’t show ads, but their third-party integrations do. Article with sources

In the end, processing and storing millions of texts, images, videos and files permanently, and hosting all those live voice and video calls, and making updates to the clients, will always cost more than what they get from Nitro and server boosting. Discord isn’t profitable; they have to make the deficit up to shareholders somehow.

At least you can block some of the telemetry with uBlock or similar

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.