In reply to Tobes:
I've also read about all the supply problems across the global bike market, but have you had any direct contact with Sonder/Alpkit? Communication has always been one of Alpkit's strongest suites, and maybe they genuinely are as much in the dark as you, but they might be able to give an educated guess if you call?
I'm toying with the idea of getting a Transmitter, hence my interest! Good luck whichever way you go. I've read lots of similar posts to yours in various bike groups over the last year, so if nothing else, you're very much not alone in your disappointment! Not that this will help much.