4 days into my new desktop installation with Arch + BTRFS partitions and subvolumes, everything is going well !

Great to hear! May I ask why BTRFS and not just simply Ext4 + LVM?

I think BTRFS has compression on top of your suggestion, but I wanted to try ! I saw it was adopted by Fedora Workstation 33, I thouht it was ready for a daily usage (: