Migration of a working Debian 11 system to another

Assume I have two Debian 11 systems. System A with custom application setup. etc. And a vanilla system B. Now I would like to transfer the whole setup from A to B. I found some links, where users tried to transfer the whole root tree or clone their system to another drive. The main effort in this solutions are to re-install grub and adjust some crucial configuration files like fstab. Can I just exclude those directories, which contain crucial configurations files like /boot and /etc/fstab from copy/tar? Or is there a tool that allows me make a backup of system A and create a boot able usb pen drive using this backup?