Fedora BTRFS Snapshot Boot and Distrobox Use Case

You do not have to use grub-btrfs here. Fedora reserves 3 kernels respectively out out box (you can adjust it according to your needs). In case there is an issue with the kernel, you can easily boot with a previous one. There is a couple of things to consider before putting /boot into btrfs partition, I think you can have a look at this: Will Fedora use Btrfs for /boot in the future?. I use snapper and btrfs-assistant, everything works normally. If you want to back up /boot, use rsync for that.