Some of the Lenovo tiny 1L machines can take a PCI card to add more ports. I've specifically seen it done with the 720q. You'll need a riser for it to fit. If you search on AliExpress for "lenovo thinkcentre tiny network riser card" or similar you'll find some examples.
Here's a different method someone used with a Lenovo M900 using an M.2 ethernet adapter. https://www.youtube.com/watch?v=RMKvhx7z3aY
There are several threads about this on Reddit, but I'm not going to link them because of all the mess going on over there. If you search a bit you'll find them though. If they've been deleted due to the protests, try a cached copy on Google.