Probably just a lot of bloatware. When I’ve been in this situation in the past, I did a completely fresh install of windows. Much smaller. Linux can free up even more space.

There really isn’t anything necessary from HP, but it also depends a lot on your comfort working with the computer so ymmv. I don’t know what’s gonna happen if 3 months down the line you need to call customer support for something. If it were me, I’d be thinking “worst case scenario I can just factory reset”, especially if I had everything important backed up somewhere.