Anyone seen something like this? I guess it’s a long shot but I thought i’d ask here.
I think that would require an in-wall powered Ethernet switch/hub, which I don’t think exists.
If that important, the closest thing would be a pair of Power-line Ethernet adapters.
https://www.amazon.com/ethernet-over-powerline/s?k=ethernet+over+powerline
Nah not important, just a wouldn’t that be nice sort of option. Even unifi’s inwall HD AP doesn’t have port activity indicators. 
The only thing remotely similar to my idea is this, although it seems to have no activity indicator.
It is a very cool product all the same: