The rootfs will be live and any crash will broke it...
Next boot will not get it autorepaired and will give you in a unbootable state !
I have this issue too often on RPi.
You must then repair the uSD from another computer !
The good way is to have a ReadOnly rootfs, then block-mount and overlay will help to expand the storage.
In case of crash or power-fault, the rootfs will work and the overlay will be checked and auto-repaired...
The worst will only be an auto-reboot !
The two methods can be "mixed".
An image customized with image builder, which integrate block-mount and a f2fs overlay as a third partition (which can be resized at first boot) will be a great idea !