OP here. I've been working on an app/platform for people to explore musical ideas. This is a drum machine that a European friend of mine created using the app. You can press the Play button in the top-right corner to start audio playback and customize the pattern being played by clicking the red squares on the step sequencer.
Disclaimer that this is made with laptop/desktop computers in mind and may not work well on mobile. The app supports binding MIDI controls by double clicking on knobs :)
If this example is too big and scary, I've made a simpler drum machine here: https://noisecraft.app/529
And many more examples can be found on the browse page: https://noisecraft.app/browse
One of my all-time favorites is this one: https://noisecraft.app/101
Disclaimer that this is made with laptop/desktop computers in mind and may not work well on mobile. The app supports binding MIDI controls by double clicking on knobs :)