Screen sharing in discord is a discord issue. It’s been possible for a while and I know there are third party discord apps that do it. Discord just won’t update their office Linux client to do it. It’s a Discord issue, not a Linux issue

I’ve never seen a microphone that won’t work on Linux. You very likely just need to tweak your audio settings. This is a common problem people have with multiple audio input and output options in Windows and Mac OS too.

Like you said, some games wont work and there won’t be anything you can do about it. That is always going to be a reality.

Performan in most games is basically the same between Linux and Windows. I wouldn’t worry about that.