I recently got a Seattle ultrasonics knife, and it was mentioned in the email associated with my purchase it might need a software update

I rolled my eyes and braced for the inevitable pretty but buggy and slow app.

It didn't use an app. It used the Bluetooth functionality built into chrome and it's derivatives to talk to the knife, update it, and perform a calibration

I've only ever used the Bluetooth and serial for flashing esp32s and similar before. It was a wonderful experience