Ubuntu is fine. Drivers are annoying on all distros (nvidia updates for me mainly, I don’t update hardware often).

I have daily driven various distros and tested a lot since the 90s and I pay close attention to time spent on customizing and fixes, and ubuntu just isn’t worse than other distros. I make setup scripts and have custom dockerfiles for webtops.

I want to like nixos or whatever fork will prevail, but it’s more work than people want to admit. I personally don’t want to have to pay that much attention to my operating system. It’s why i ditched gentoo almost 20 years ago. I don’t want to lurk forums for fixes and tweaks. I also make sure hardware I buy doesn’t have glaring compatibility issues.

If Ubuntu rubs you the wrong way but you are fine with most of it, just use debian.

If you google “skr mini e3 v2 pinout” you can find 5v and ground pins. The question is how much load is already on it’s 5v regulator and how much are you adding.

You can power the pi from a buck converter or from whatever else.

They apparently make an addon 5v buck converter for that board.

Using a multimeter could help avoid frying more stuff.

My best advice is to avoid people who yell at you. You can express your boundaries and let whoever know how that makes you feel, and what you can’t accept.

If the yelling isn’t retaliatory from some bad thing you did to them, you could also ask them if they are okay.