It’s still possible to make a bootable backup on an M machine with Sequoia 15.2. In order to do that, you have to use Apple’s installer to install the OS onto an external disk, and then use that disk for your data clone backups. At one point there was an article on the CCC website that detailed this approach (it might still be there, but I couldn’t locate it just now). I have an external bootable backup disk that I created using this approach and it contines to work fine with 15.2. Note however that you have to update the OS on your external disk separately from the internal disk. To do that, you have to actually boot from the backup disk, so it’s an extra step whenever there is an OS update. But it solves problem of being able to boot to a clone of your data disk when you need to continue working.