@amosbatto, this Ethernet adapter (AliExpress 1005001623728670) works with Calamares installer (with Byzantium for sure) out-of-the-box, meaning it should be working with Librem 5 and it will be useful with Librem 14 as well. Besides, it already works with the PinePhone USB Type C port.
idVendor=0bda, idProduct=8153
Product: USB 10/100/1000 LAN
Manufacturer: Realtek
Please add it to the list of compatible external devices, if no objections (or wait for another, based on Purism hardware, confirmation):