Yes absolutely! I'm a GrapheneOS user myself so understand not wanting to have to go through the play store if you can help it.

I believe you have to make the source code public (please correct me if I'm wrong). I'm more than happy to do so, I've used a whole bunch of open source stuff to build the app so it only seems fair, I just need to make it a bit less messy and something I don't mind being public.

Yes, not just public, but also licensed under a license that permits free redistribution, modification, etc. This is awesome!