They could maybe add an outdoor gym for adults? Something that wouldn't require any electricity to run, and wouldn't break down in the rain. Maybe it would require some upkeep from time to time, to prevent rust and such, make sure the hinges are oiled, etc., but not much else. I think that would be lovely.
As for big lots, you don't need to build and decorate the entire lot if you don't feel up to it. I put a fence through the middle of the big lot in Del Sol Valley and pretended the other half doesn't belong to the household living on the lot. 😁