Creating unlimited number of training programs with (for example push-pull-leg, where I can do them any day, without being restricted to doing for example push day on monday)
I would be interested in this too. I have been using GymGoal Pro for about four years, and it is quite flexible. I did a super quick google search just now and do not see a public API, but it has the other two features in your list. It also includes support for other exercises (including cardio and stretching). Oh, I think it is only Apple, not Android.
The nonprofit I work at is building use cases up for things like bodybuilding, more detailed fitness, etc. We also intend to make our APIs public.
I know this is not quite what you’re looking for, but if you or anyone you know is interested in collaborating on something like this instead of building it themselves please look our way!