This is amazing and very very promising. I was looking for something like PineTime but apparently my google skills weren't good enough.. Thanks a lot for the help!
I personally have gotten better stability out of a BangleJS with OSD than I got with a PineTime. OSD isn't perfect but the source is open and it wasn't too difficult to build locally (you mention you are an iOS dev, and OSD is a Java Android app, I bet there are still many similarities).
I'd wager that you can quite rapidly adapt OSD to become what you need. Maybe even upstream a nice little species selector feature perhaps?
The main OSD maintainer is a rather nice fellow. I think he'd be delighted to hear that someone found OSD and had use of it.