Hi, I just bought a seaboard block and I am quite happy with it. I am a linux+android user since years, so I would like not to change my environment to fully appreciate the potential inside this powerful little keyboard you made. I own a samsung note 9, that as far as I can understand is still one of the highest end smartphones around. I have the noise app installed, but it works only as a soft bank. If I dare to record or play more than a couple of notes simultaneously it begins to have unacceptables latency and cpu "cracklings". I do not believe the app is performing differently on Pixel phones.
I am aware of the long debate on android latency issues, but I also know that the hardware specs and the work that Samsung began with Pro Audio should have overcome some of this problems... I also remember a keynote with some guy playing a seaboard rise in booth at I/O 2017 stating that the new API's of android O where doing great for music in android, but... I am P now and it seems always a demonstration stage.
You are not requested to make noise working on the full android market spectrum, obviously. but specs should matter and you should select a bunch of models and make it work. I shifted to Samsung just since a couple of months, so I am no fan, but I think that their top line should be included in this selected bunch.
Furthermore with all their fancy DEX stuff, that I hope will rise in functionality, in future, when you'll release it (are you? true?) it could be interesting to compile the full version of equator for linux (that should not be so demanding for you) for ARM based devices.
So that creators and makers all over the world could go on even with RPI implementations.