Moshe, thanks for sharing. This simple of type setup (add a jack to the speaker box and use earbuds/headphones) makes a lot of sense and I'm handy with these projects. I'm shopping cheap wired earbuds to get started. Comfort is the first priority and I can move up later if I need better noise suppression. My concern now is too much stuff connected to my face (canula, sunglasses, a sun mask, and now earbuds) and all competing for my ears to hold them up. Probably a good reason to stick with the boom mic.
thx, JJ

Connect them in parallel to (or in place of) the existing speaker. The
speakers are usually around 4 to 8 ohms, simple earbuds or headsets
around 30 ohms, so it should be OK to add that small additional load
onto the radio's output. You can add a 3.5mm headphone jack onto the
speaker's box if you want to easily connect and disconnect. Wire the
two sides of the headphones together to the mono speaker line. If you
want you can also wire that jack so as to disconnect the speaker when
the headphones are plugged in. Like a transistor radio in the 70's. If
you're not handy with that wiring/soldering aspect, ask a friend who is,
it's an easy project.

And yeah if you already have a boom mic and PTT on the stick why disturb
that arrangement?