I did get a chance to test with a Fitbit recently. It technically worked, but not all that well. The thing is, the Fitbit only advertises every 2 seconds so latency is a bit high. But worse, its apps really want to be connected to it often to sync; and whenever it's connected, it stops advertising and the detector then can't pick it up.
At this point I don't plan to modify the board much but having it read environmental sensors would be a cool feature!
For that, would be nice to make little beacons that read sensors and advertise/broadcast the readings every few seconds. Then they could be very low-power, run on coin-cells for months, and could be placed anywhere instead of needing it to be hooked up to USB power like the main board is. Like these: https://sen.se/peanuts/ I'm curious if it could read them.
As for enclosures, I know. I would love to have some nice ones but at this point I'm making too many boards to 3D print enclosures, but too few to afford injection-molding tooling to make a custom case.