I use and like Restic but I wish I could easily have "write only" keys like I do with tarsnap so an intruder can't delete all my backups. I heard there's a way

I use and like Restic but I wish I could easily have "write only" keys like I do with tarsnap so an intruder can't delete all my backups. I heard there's a way to have an "append only" backup or something like that. Is it possible to still prune old backups from time to time?