I have a Toshiba 4TB formatted in exFat.
I use the adapter that comes with the Pixel 7 to connect to the USB-A from the HD (micro-B).
I have to connect 3 times for it to work.
With the Pixel unlocked, I connect the external HD. It turns on the light from the HD but nothing shows in Files. I can see the USB menu (top taskbar) and the only option is "USB controlled by device or not). I try to change to this device (phone) but it doesn't go.
I unplug the HD and plug again and this time it asks to format the HD. It shows a white screen with two options. Use as storage for the phone or transfer between the devices. For both it wants to format the drive (and delete contents).
So I wait for the drive to go idle and turn off (light from HD turns off) to unplug and plug again.
But now it shows the option in taskbar to see the contents or eject the drive. I open Files and I can see the drive and access the contents.
It's bothersome having to connect 3 times until I'm able to access the files and I don't want to risk corrupting the drive and losing the content.