Have you perhaps considered that in some channels bits aren’t a huge thing because that is by design of the streamer? It sounds like you’ve been collecting raw data from channels without a streamers permission and if you’re not in direct contact with those streamers then you have no idea what own thoughts on bits are, the income from bits might be low intentionally.
There are pros and cons to bits, and a lot of streamers don’t mind bits because if someone wants to use them then sure, it would be silly to stop that revenue stream, but they might not actively push for the use of bits and this can be intentional.
I find it much more likely that people didn’t steal your idea, but just had the idea on their own, or as Barry suggested had a feature request from someone else. At the end of the day timers, overlays, all of it is rather generic and something people will easily come up with on their own. If they copied the exact design outright then maybe that would be something to complain about.
As for access to Twitch’s new interactive overlay thing. To my knowledge all of those with access right now have had well established apps beforehand, or at least proof of concepts. You have an idea, and currently no users. Make your app, prove it has value to Twitch, Streamers and the end users who will be interacting with it, and then try to see if it should be integrated with Twitch’s interactive overlay.