Works very well! WiFi, camera, calls, speakers, bluetooth work out of the box. Headphone jack requires configuration.

Install GSI on Oneplus Nord N100

Enable USB debugging and connect phone to computer with adb installed. Then:

# unlock bootloader, device will wipe and restart
adb reboot bootloader
fastboot oem unlock

# re-enable usb debugging and again connect through USB with computer
adb reboot fastboot
fastboot erase system

# it will print either Erasing system_a or system_b. In the following I assume system_a was erased; if it was b, change commands accordingly.

# with phhusson GSI, system partition needs to be larger than stock. so delete the product_a partition to make space (see https://developer.android.com/codelabs/using-android-q-gsi#3)
fastboot delete-logical-partition product_a

# when flashing the system, disable integrity checks on startup to allow image to boot
fastboot --disable-verity --disable-verification flash system_a system-roar-arm64-ab-gapps.img

# wipe again, then reboot
fastboot -w reboot

Fixes

• To get the headphone jack (3.5mm) to work, go to Settings > Phh Treble Settings > Qualcomm features and select "Use alternate audio policy".