Install Ubuntu on an F2FS Partition:
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*Grub does not work on F2FS, so your /boot partition must be a ext4 or btrfs for it to work.

sudo apt update
sudo apt install f2fs-tools

Modify /etc/fstab for your existing file system for root to be f2fs.

Mount old drive to a wanted drive (in my case it will be /opt/main).
Have another folder for full drive backup (in my case it will be /opt/backup).

Mount and backup old partition:
sudo mount /dev/sdaX /opt/main

sudo cp -a /opt/main/. /opt/backup
sudo umount /opt/main


Format old partition to f2fs and restore:
sudo mkfs.f2fs /dev/sdaX
sudo mount /dev/sdaX /opt/main
sudo cp -a /opt/backup/. /opt/main
sudo umount /opt/main

You now got a F2FS root partition for ubuntu!

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Source: https://howtos.davidsebek.com/debian-f2fs.html
Date in Vivaldi: March 18th 2021