Thanks @bi4smooth for the reply. Any help/hints are always appreciated!
In this case I was the only one seeding, so it wasn't the case of me not being selected over other seeders. I'm certainly not a torrent tech expert either, but I know there are different methods of seeders/peers finding each other (DHT, PeX, etc.), so I suspect there's some method that isn't working, and the clients trying to connect to me aren't configured to use the methods that I have working.
I ran your UNIX command in terminal and I see qbittorent listening on 8080 for the web interface, but there is no other listing for qbittorent. I expected to see the port that I added for incoming connections, but it's not there. So that may be a clue.
One additional data point since I originally posted. I ran a Windows instance through Parallels and ran qBittorrent there. That instance was able to connect to the peers that the Mac instance couldn't. So more clues that it's an issue with Mac networking (or the Mac build of qBittorrent) and not my router.
Thanks again for the reply. Enjoy the hunt for the smooth guys (leaves more hairy guys for me 🐷 )