My main issue is the lack of support for serial (so, no USB support): https://github.com/microsoft/WSL/issues/2195.
Other that this I love Windows 10 + WSL2 as a dev environment.
It's a little clunky, but you could use a Windows RFC2217 remote serial server with socat on the Linux side to make a virtual serial port tied to a real one. I've done this (albeit not with WSL), and it did work.
Too late to edit, but there's also an unapplied pull request that seems to make usb passthrough work:
a) It doesn't play well with deep sleep mode, and crashes. Perhaps it's been fixed, I don't know, I just disabled deep sleep.
b) The networking is different than WSL1 and requires odd workarounds for things like X11 to work normally. I had to use a 192.168.1.x address for DISPLAY instead of localhost. Which required some VB scripting to reliably work for me.