TriLink

@leon_s_k have you looked for the official nintendo one?
https://store.nintendo.com/wired-internet-lan-adapter-nintendo-switch.html

It's more expensive and only usb 2.0 but might be easier to get a hold of. I've seen others mentioned to work but idk if you would be able to get a hold of them.

@rjejr This is the one I have, seems to work well enough. Tho I honestly don't play a lot of docked switch. I got it cause it was the one I kept seeing recommended when I researched for one.
https://www.amazon.com/UGREEN-Network-Ethernet-Supports-Nintendo/dp/B00MYTSN18/ref=mp_s_a_1_4?dchild=1&keywords=nintendo+switch+ethernet&qid=1601879348&sprefix=nintendo+switch+eth&sr=8-4

@leon_s_k
This is the one I have, seems to work well enough. Tho I honestly don't play a lot of docked switch. I got it cause it was the one I kept seeing recommended when I researched for one.
https://www.amazon.com/UGREEN-Network-Ethernet-Supports-Nintendo/dp/B00MYTSN18/ref=mp_s_a_1_4?dchild=1&keywords=nintendo+switch+ethernet&qid=1601879348&sprefix=nintendo+switch+eth&sr=8-4