According to this link Unable to start container with sysbox runtime after kernel update. · Issue #596 · nestybox/sysbox · GitHub it seems sysbox is on the cusp of some changes… switching over to idmapped and deprecating shiftfs.
I believe kernel 5.19 added ID-mapped-mount support for overlayfs (need to double-check). If true, then we will adjust sysbox to use ID-mapped-mounts for the container’s rootfs too, and at that point ID-mapped-mounts would essentially replace shiftfs for all practical purposes.
However I have not been able to find any discussion of how or when this is being implemented.
I appreciate any updates on this topic.