I don't know what your budget is or if you're willing to carry another phone around, but pretty much any android should work with urndis Pixel6 and newer won't as they use cdce but don't appear to be supported by NetBSD. I have a Pixel 8 and it does not work with NetBSD.
I have a Pixel 4a (AC wifi), and get 200 mbit with tethering on NetBSD. I have seen just shy of 400 mbit with a Oneplus 8 (AX wifi).
You can find Pixel 4a for ~$70 on ebay. It's a relatively small and light phone. I picked up the Oneplus 8 for $75 with a burned in screen, but it's really minor. You can probably find another phone for less $$ or get something with burned in screen or blemishes since I presume you would only be using it for the tethering.
