I’m accustomed to the imperial system. But agree that metric is better.
Some metric stuff I have no trouble with. I have a good spatial sense of the distance of a mm, m, and km. And can do a rough miles to km (and vice versa) conversion in my head. I have a good sense of how much a kg is and similarly can do a rough conversion to and from lbs in my head. But while I understand that a gram is 1/1000 of a kg, if handed a small object and asked to guess how many grams it is, I’d fail miserably.
Celsius I can’t ever remember the conversion, but I’ve had enough exposure to it that I understand if it means cold/cool/warm/hot weather.
Almost any distro will work for pretty much all of that. Only potentially limiting thing I see there I don’t think that the Mullvad VPN client is generally available within distro repositories. Their site says it has clients available for Ubuntu, Debian, and Fedora. So perhaps pick from one of those?
For the steam link question, I know if I have a game running on my desktop it presents me the option to stream to my laptop (both Linux machines). I assume this is the same functionality. I don’t use it so can’t speak to how well it works.
Edit: It occurs to me this comment lacks a recommendation. Within the three listed supported distros for Mullvad, I think I’d recommend Fedora for you. Been some years since I used it last but I remember the installer being fairly robust and intuitive while still easy to use, and a pretty rock solid system once it’s up and running.