I've already tried. None of the recruiting firms have been able to lead me to job offers. I got a few interviews, but that's it.

There's a lot of detail in my original post, so you would need to provide more detailed, personalized advice. "talk to a recruiter" would be already attempted for someone that's been on the job search as long as I have.

Check out Rural Sourcing. They look for bargain devs specifically.

as long as you relocate to one of their four locations...

https://www.ruralsourcing.com/about-rsi/development-centers/