Is some sort of "personal" jammer hardware plausible?

No. The only solve is to start voting and voting for people that actually fix these problems instead of bowing to corporate interests over people interests.

it would be interesting to see if the "camera light has been tampered with" 'privacy mechanism' could be remotely triggered by some carefully timed application of electromagnetic energy pulses ;)

Well, cell signal jammers are illegal. I could see the possibility of something like a Meta-produced device that could be set to disable recording by Meta glasses in the vicinity. That seems different in scope. But lol on that.