https://www.sensorwatch.net/ https://www.sensorwatch.net/ I haven't made one myself because last I checked it was a hassle to ship, but this might be what you'

https://www.sensorwatch.net/ https://www.sensorwatch.net/ I haven't made one myself because last I checked it was a hassle to ship, but this might be what you're looking for, F91-W exterior with minimally smart replacement innards.