I’d describe it as making computer systems reliable.

Why is that? What do you feel is the downside?

Yes, kind of.

Someone might correct me if I’m wrong but it’s that, plus extra tooling to redirect the stuff that needs to be writable, plus more extra tooling to allow you to temporarily unlock the read-only parts in order to do system updates, plus a system updater that puts the whole system more-or-less under version control.

I only use it incidentally but my biggest gripe is the total inability to perform its one function of teleconferencing.

The bit where it lags the audio badly and then speeds it up to catch back up to real-time is absolutely infuriating to listen to, and such a failure of a tool that had. one. job.

implement the Windows PIN thing for startup on my PC

If you’re that specific in your requirements, you’re gonna have a bad time. I don’t think Microsoft makes “Windows PIN” for Linux.

Sometimes it makes a network connection work temporarily.