Cool, and then there’s NEVER any problems with different paths? With back and forward slashes? With the limit on path length? With missing permissions on the file system requiring weird workarounds?

Nope. The language we use handles that for us. I don't think path length has been an issue for a while now?

Most importantly, your server is likely not Windows, yet you test on Windows, and that’s never ever been a serious source of issues?

We use serverless functions using Linux and it's never an issue. My previous employer, we had Windows servers and Linux based containers, and that wasn't an issue either.