The FAA has decided that unregulated drone flight is an issue, and no matter what, they're going to tackle it. So I'm happy to see any solution that allows for the continued existence of the DIY part of the industry.
In my mind the "ideal" solution for DIY aircraft is a separate RC receiver-sized transmitter, powered over BEC, that you add to your aircraft when you are flying in conditions that require Remote ID. The transmitter would become another fixed cost in the hobby, but you could use it on whatever aircraft you're flying -- It would be linked to a pilot, instead of a particular aircraft. I have zero knowledge of RF physics and engineering, but I'd be happy if that was possible without a heavy transmitter and significant power consumption.