I've successfully applied attended sysupgrade with the following devices:
TP-Link Archer C2600
TP-Link Archer C7v5
These devices have flash memory and use squashfs.
I hesitate to apply attended sysupgrade for pi-like devices, which use an ext4 image on a sd-card. Therefore my question: Does attended sysupgrade work with ext4 images the same way as with squashfs images?