It is great to see that this is accessible and possible with limited effort/budget!
On the higher speeds, it remains difficult: In the datacenter, 10G ethernet is often standard or even outdated. But for non-mains powered systems, even 10G uplink is hard to come by. I would love to have a switch with 25/100G uplinks in a smaller-than-19"-rack form factor with 12-40V DC power. Building one as a side project might still be too complex - if you would get access to chipsets at all.