Just windows, I had windows 10 installed on my laptop and was constantly fighting with windows update so when the system broke (wouldn't boot) I finally installed Ubuntu. These days I use arch BTW.
You can just open them, all the ones at my Uni have tubular locks that can be opened as fast as using the key.
I'd just like to say that if something says Ubuntu support it will very likely work on all Debian based distros unless its something really low level and your running one that swapped out systemd or something. They normally just mean that they ship their software as a .deb file and even that can be installed on non Debian distros if your willing to do some special stuff. Also as for drivers/firmware I've never had any issues except when trying to use a distros that doesnt include non-free firmware.
I like to tinker with it and the lack of restrictions on low level stuff. The ability to completely change anything about he system that is restricted on other platforms. No data is sent from the system unless you actively enable it. Its stable, I have a raspberry pi that can run for months without error whereas windows bluescreened once every 2 weeks with regular usage. Its free.
@Bananable
@feddit.nl