Any privacy considerations regarding allowing inbound connections for a Tor full node?
If you are running -onlynet=onion, there is no need to open any router ports. Perhaps I misunderstand your question. 

If your chain state is caught up, and bitcoind+Tor is properly configured, you should be serving data to other nodes, even behind an otherwise locked-down home router. 

What result do you get when running 

$ bitcoin-cli getpeerinfo | grep true