Advice on moving NCP from SD card to USB SSD

my NextcloudPi server is running on a Pi 4, the data and database is on a USB SSD (1 partition for whole drive).
Now I want to move the system ( / ) to the USB SSD and keep only /boot on the SD card.
The plan is to resize existing partition on SSD, to create a 30GB partition for / , rsync / from SD card, change fstab and config.txt accordingly and reboot.
For the repartitioning I will plug the SSD to my Linux Mint laptop and use gparted.

Will this work?

Of course, before doing anything, I will make a NCP backup with data and a dd copy of the SD card.

Dont know if this still works on rpi4, I used Berryboot for that on rpi3.

My goal is not to reinstall, only to move the system. You mean that reinstall + restore from backup is better?