Very few programs require anything complicated to get them working. A lot of productivity programs don’t support Linux though, like anything from Adobe, but there are usually alternatives, and if not can often be run in a VM. This probably doesn’t matter for you though, since you don’t seem to be particularly technical (not an insult). You probably know what programs you need that may not work. If there’s nothing like that then you’ll be fine.
Yeah, anything Adobe won’t work, but there are plenty of PDF viewers that do. Also, yes, Steam, VLC, and Firefox all work perfectly fine on Linux. You shouldn’t have any issues.