I’ve been using Proton for about a year and a half now. It’s been really good for my needs, I started on the free version but then decided to pay to help support them and to get access to everything else (specifically SimpleLogin).
It would be the OS (in this context) that you use most often on a daily basis. When the OP logs onto their computer, they would be using Linux as opposed to Windows.
I’ve been using Pop!_OS for about a month now and it’s been great! I only had one issue (completely my fault) which caused me to have a black screen upon login after a reboot.
I’ve switched from Windows 11 to Pop!_OS and don’t have any complaints. It looks different to Windows (no start menu like windows) but that wasn’t a turn off for me. If you want something that looks closer to a windows machine, Mint is a great option
I was looking at getting a laptop from System76 but the shipping to Europe is insane. I’ve heard some good things about Tuxedo Computers. I don’t have personal experience with any of them so can’t comment on that