Hi akc3n,
Firstly, thanks. Secondly, I am waaay out of my depth but doing my best.
When I go to chrome/ flags, this message is highlighted ;
Automatic detection of WebUSB-compatible devices
When enabled, the user will be notified when a device which advertises support for WebUSB is connected. Disable if problems with USB devices are observed when the browser is running. – Mac, Windows, Linux, ChromeOS
#enable-webusb-device-detection
And to the side: "Not available on your platform".
In site settings/ permissions /USB/ Pixel 9a is listed, in a 'ask before allowing'
But under site settings/content/ I have no 'sitedetails'.
The 9a seems permanently unlocked in greyed out mode.
After doing that, tried plugging in, but same result.
The mystery to me is that downloading GrapheneOS on to my Pixel tablet using same cable/phone worked perfectly.