Pixel 9a and tethering. Can't get it to work

Yep :smile:, we have no way to know if the specific device will work, but the concept in itself is not completely wrong, at least starting from v7.x, though there are reports of some devices working also on v6.x, namely some Samsung devices:

I seem to remember that the Pixel's (at least earlier models) are somehow more picky/tricky than other devices so it may be the specific device/Android version that creates the issue[1].

[1] As a parallel example, years ago, it was common with PC's in the world of BartPE's the exclamation "Oh, noes, it's a Dell!" because the good Dell guys used to make some (slight) BIOS modifications that made booting a PE more troublesome.