I guess you didn’t look around very well then, because it most certainly does offer you a choice of installing on btrfs, as well as on xfs, jfs, f2fs, and a whole batch of other Linux-native filesystems.
You probably need to rebuild the initramfs.
mkinitcpio -P
You’ll have to chroot into the btrfs installation from the live USB or from the ext4 installation.
The following tutorial () is not really about your kind of problem, but it describes the procedure for chrooting into btrfs, because manjaro-chroot cannot deal with btrfs subvolumes.
You’ll probably also need a btrfs-capable version of grub, because the default grub cannot handle sparse files. Inside the `chroot, run the following command.
