hello, It's a pretty niche idea but here's what I'm thinking
firefox --profile /tmp/nonexistent
gives you an error. But what if I want to make a new profile at this location? The solution imho would be to introduce a --createprofile or similar commandline flag, like this:
firefox --createprofile --profile /tmp/nonexistent
and I think this command should just create a new profile at that location and then exit