Though something I half-miss is using my own software as I build it to get a visceral feel for the abstractions so far. I've found that testability is a good enough proxy for "nice to use" since I think "nice to use" tends to mean that a subsystem is decoupled enough to cover unexpected usage patterns, and that's an incidental side-effect of testability.
One concern I have is that it's getting harder to demonstrate ability.
e.g. Github profiles were a good signal though one that nobody cared about unless the hiring person was an engineer who could evaluate it. But now that signal is even more rubbish. Even readmes and blog posts are becoming worse signals since they don't necessarily showcase your own communication skills anymore nor how you think about problems.