Here are some backup programs I used or tried to use or rejected because they do not fit my requirements. Here are the good, the difficult, and the incomplete.
I backup several computers, notebooks and desktop workstations, running Linux and Windows 10. I need fill disk image backups plus file backups for data partitions. I could run backups over a network and do not want to limit my backups to the point of requiring a network. All the machines have decent USB speed for backup direct to external disk.
October CMS is based on the Laravel framework and stores content as flat files. Flat files offer speed advantages when compared with the average database and Laravel offers speed advantages compared to the monster Symfony framework.
October won a CMS award in 2018. Grav won the same award in 2017 and 2019. Grav might be the first CMS to look at if October is not exactly what you want.