The 'upgrade to next version of ubuntu' has gotten pretty good these days.

The only thing I would make sure to do is to have a separate home partition / volume so if you had to blow the underlying OS away after a botched upgrade, it's easily doable.

For the life of me I don't understand why having a separate area for your personal files isn't the default on every OS. Just pick a reasonable size for the OS part (20-30G?) and give the rest to /home

The laptop started with Windows 7 (the best one btw). Switch to Ubuntu was done years later when I handed it over to my parents.

You are right about the Ubuntu upgrades though. Over these years I'd just randomly press update to get out of EoL'd versions when I was around. I think I just went over 4 major versions in a few hours. It just downloaded, installed and restarted without any problems. One outlier was an issue with nvidia driver packages after update, for which I had to consult google.

The laptop is 18 years old, Ubuntu was installed in 2017.