This app was mentioned in 5 comments, with an average of 1.40 upvotes
I'm using DRC synth ATM, there is an bunch of presets. Only used it once so I do really know much about it but it got me a nice sound so ����.
https://play.google.com/store/apps/details?id=com.imaginando.drc
When you say you've tried "bandlab, soundtrap, and a bunch of other garbage programs" do you mean webapps or android apps? I have lag with webapps, but most android apps I've tried are fine. (The bandlab webapp lags bad for me, but the android app is acceptable.)
Try DRC: its free to play around with and doesn't lag for me (though it can be flaky, and crashes from time to time, but I bought the full version when it was heavily discounted, so I'm not complaining). OTOH, Flowtones Edit (also free to play around with), lags really bad. In fact I can have both DRC and Flowtones running at once listening to the same MIDI device, and when I play notes, I can hear them sounding at different times!
I really like this one:
https://play.google.com/store/apps/details?id=com.imaginando.drc
Though I definitely need a better phone for the more complex patches.
Real synth there is just one worth mentioning on Android: Imaginando DRC.
https://play.google.com/store/apps/details?id=com.imaginando.drc
I like DRC for synths.