I can tell when there are electronics turned on around me even if they aren’t intended to make noise, because they all seem to give off this kind of almost imperceptible high pitch whine. Not enough to be bothersome, but just enough to know something probably has current running through it.

Same here. But that’s basically just good hearing.

Most of them explicitly do NOT count against residency.

Beware though, many of those are limited to a small number of years.

That sounds like a job for… a spreadsheet.