What do you do on your laptop? For example, engineering students and STEM hobbyists probably want Windows, maybe Linux depending on their interests, specced out to run CAD or whatever simulation software their major will dictate. Graphic artists and photographer hobbyists might want Mac.
Framework laptops can ship with Windows already installed. You can also install Windows or Linux yourself, but Linux is not required.
You mention you don’t know Linux, but how comfortable are you with hardware? Can you open your current laptop and add memory? Are you interested in upgrading your laptop hardware periodically or is it going to be a chore you avoid?
Your question on 8 vs 16GB memory should be driven by your use. Personally, 8gb isn’t enough for me anymore, it locks out a lot of newer games and programs that I want to use. Does your school recommend OS and specs for your major? Make sure those are met at a minimum.