[jwr]

Please don't get me wrong: I really do appreciate the hack value and I absolutely understand choosing this route to scratch a personal itch!

My point was more general: I see a lot of things getting built using Linux that really have no need for this level of complexity. And it doesn't come free: complex systems are more fragile, there are more things that can go wrong.

In this particular case, I'd recommend taking a look (for example) at the Seeed XIAO nRF52840 module and Zephyr: around $10, very capable CPU, very good Bluetooth stack (Zephyr+Nordic), USB-C connector.