[londons_explore]

In my experience, hacked together arduino projects easily exceed a 25 year MTBF (if you exclude day-1 failures because someone did something stupid like wiring it backwards).

However, ESP32's do not (they seem to require a power cycle every few months - and in my view, that is a failure). R Pi's certainly do not (they require human attention for software updates, which IMO is also a failure - and even if you don't update them, there is almost certainly some tiny memory leak and it'll need a reboot in a year or two anyway).