One of my dream projects would be to grab some off-the-shelf switch IC and build OSHW switch around it with fully free blobless Linux based software stack. Something like SparX-5 [1] could work here, and the vendor software is already Linux based (but presumably absolutely horrible). The problem is that you'd need fair chunk of cash to get anywhere, so this basically needs a kickstarter or something to get going.
You might be interested in some of the stuff Andrew Zonenberg is working on: https://ioc.exchange/@Azonenberg. I don’t have a link to a specific post, he usually has a couple of things on the go and they all get interleaved. Pretty wild Ethernet stuff in there!
[1] https://www.microchip.com/en-us/product/vsc7552