Glad you like it and happy to hear it was easy to get started, that is one of the main goals of the project :D
I have some things planned for STEPPER, LFOs would be feasible within some constrains, though it may take a while for me to add them.
One of the main things I will push for next version is pattern chaining so that we can have a pseudo "song mode" available, I'll see if I can incorporate your suggestion after that. If I understand you well, you would like to switch patterns or channels while on trig selection mode right? I could see that being useful, though I'm also thinking on adding a "marking" mode so that you can copy-paste multiple trigs and was thinking select + d-pad for doing that. Unfortunately the GBA has a very limited set of buttons!
After that's done I want to do a parameter UI update so that I can include a "chance" and maybe a "panning" knob per trig.
Just keep in mind these updates will probably come out slowly, this project is not fully self-sustained at the moment of writing and can't afford to make it my full (or even part) time job.
I'm working on it when I can though and would love to push a few more updates for sure.
Cheers!