Internet Connection Sharing with macOS and a Monitor

I get bored.

The day before the CenturyLink connection keeled over and died I got a Raspberry Pi for messing around. I hadn't even formed a thought about what to do with it, so I started with "make it work," and then "move my Emacs config over to it," and I was rounding the corner on "get a few mount points from the Synology" when everything went to hell and I started living off of iOS/iPadOS hotspots.

With a relatively stable "iPad as jumpbox" config going on, the Mac Studio has a consistent connection. The Pi has been sitting on the LAN, but it can't talk to the outside world. 

I realized my Dell monitor has an Ethernet port. The Mac Studio sees it as "USB 10/100/1000 LAN." So I plugged the Pi into the back of the monitor, turned on Internet connection sharing on the Mac, and  the Pi started seeing the world. Since it was able to advertise and be seen on/by Tailscale, I'd be able to get to it from anywhere.

Then I had the bright idea to just move the cable running from the switch to the upstream EdgerouterX into the monitor's Ethernet port, and the whole house is now back online: the Mac Studio is providing DHCP leases, the WLAN is useful for everything wireless in the house, etc. etc.