If you want to boot safely into Android you need a modified vendor image with /vendor/etc/fstab.qcom edited by removing the fileencryption- or encryptable-option from userdata.
I am not sure if you can remount r/w on device, I think the image on your PC and editing + flashing vendor is needed. In your case you need to reboot in fastbootd mode for the super partition to allow updating vendor.