. (I haven't done multi-boot for many years now.)

[Ralf Mardorf]

Hi,

consider to install FreeBSD, but for a transition test period to
temporarily multi-boot or at least to keep backups of the Linux
installs.

You could copy a complete Linux install or backup to an archive, while
booted to another Linux install or using a Linux live media by a simple
"cp -ai" or "tar --xattrs -czf" and if necessary simply restore it.

A backups of MBRs not necessarily could restore a bootloader, but it
doesn't harm to backup the MBR , assuming MBR is used by
"dd if=/dev/??? of=mbr.bak bs=512 count=1". At least restoring an MBR by
a systemd-nspawn (as a replacement for a chroot) from a live media is
easy to do.

Regards,
Ralf