> I'm not an expert in anything, but I know a bit of everything that is required to ship something that works
The landscape is always changing, potential employers change their requirements, so you need to know $framework or $language of the month. My advice is be agile and adapt. Don't get set in your ways with a strategy that only works for you.
Excellent. Today you might have to work a little (ok a lot) harder to get a job than a year ago but a developer who has a portfolio has a chance, I think the project management experience is worth something too, particularly in a startup. You might take a pay cut though.
The only reason I can see you not being taken seriously is that you might seem too expensive or that "stepping down" into more of an individual-contributor role may be seen as incomprehensible and scare people away.
Depends on what salary you are looking for. If you want the coveted FANG jobs, as I understand it, you'll have to grind leetcode. There's a bit of a downturn right now, so don't let that dampen your efforts.
quickest way to hate your hobby, if you're not careful what company you fall into
If that's what you want to do for a living, apply for PHP roles. 20k+ starts project, that's a very good story to share during an interview. If you know how to communicate, which I believe as a Senior PM you are, then you can look into leading a project, as long you are clear and frank about what your limitations are you are fine! Good luck ;)