Does anyone have more context on how this would be used? Is this like an alternative to using a midi keyboard to control synths? Is the appeal of it that it is small and meant to be played one handed while your other hand does something else?

You configure a preset, then touch to change presets while playing instead of kneeling down. Its like a remote control for MIDI effects pedals. Probably more useful if you have complicated live setup with a long setlist filled with a lot of effects.

There are lots of pedals these days that are designed as performance instruments in their own right. Check out the Erica Synths Nightverb; it's all chonky knobs and it doesn't even have stomp switches. You'd never put it on your floor.

Storm Summoner takes a pedal with lots of parameters [that would normally be set-and-go] and gives it that missing live performance UX. Singers in particular could use the sensors to modulate their voices.

What excites me is the flag-based system described in the review video at 11:45. You can set up stuff to happen (launch an LFO?) in response to other things that happen, like a value crossing a threshold. That takes it out of the realm of a dumb controller, and we already have enough dumb controllers.