Ubuntu uses GDM: https://wiki.archlinux.org/title/GDM
Ubuntu uses GDM: https://wiki.archlinux.org/title/GDM
I always use draw.io
Yes, cracking .NET app with dnSpy is way easier than raw x86 Assembly. I cracked some bought software we use at work, because the stupid DRM made my job harder. Lucky for me because they were written in .NET. I also bypassed some limits set by the app. I tried IDA pro but the gui is already complex. You also need to know how .exe file works and how it gets loaded in memory with the libraries.
D4 reflection works without battle.net: https://d4reflection.org/
Hide user from login list
The users for the gdm user list are gathered by AccountsService. It will automatically hide system users (UID < 1000). To hide ordinary users from the login list create or edit a file named after the user to hide in /var/lib/AccountsService/users/ to contain at least:
/var/lib/AccountsService/users/username
[User] SystemAccount=true