

Ok we’re talking at cross purposes.
Yes, mullvad has a noble repo, it doesnt have a xia repo (which is the mint equivalent version name)
Attempting to add the mullvad repo using the old ubuntu instructions failed because noble =/= xia
Yes you can work around that but its not beginner level.
Op asked if Flatpaks was the answer whivh imho it isnt, the best answer is downloading the .deb
Yes Mint is a good choice for your migration. It has been put together in a way that makes it intuitive for a windows refugee. The menu layout has the “start” (mint) button bottom left with your apps in there.
The system apps are named obvious things like “software manager” and it has default apps installed to get you going.
Being derived from Ubuntu it is the best supported platform for commercial apps/games but with Ubuntu’s weird choices (snap etc) tidied up.
It’s the most recommended linux distro for beginners for a reason. It’s a solid reliable well thought out platform