For the more compact electric units, you see relatively high reports of mechanical failure in the motor or gearbox. Tons of that with the VS3 and there have been a fair number with the lagom mini as well, although the lagom mini has been revised and I think the current iteration is supposed to be better? (Also, obviously you can only infer so much from reported failures online, as the folks whose grinders don't break are less likely to announce it.)

The new grinder from the ridiculously named MHW-3Bomber which looks a bit like a beefed up VS3 seems interesting, but no way to know about longevity. Turn SK40/SD4 is pretty small, folks don't generally love it compared to higher end grinders but I don't think there's a lot of reports of breakdowns.

Lots of folks apparently use drills with hand grinders as an alternative solution.

Re: the mechanical issues these may be more of a concern if you grind lighter roasts