I hope this is taken as an operational understanding. Some in the community get upset with those of us who do NOT do what you refer as traditional.
I say this as 'traditional' has NO meaning to us. There is the understanding in the Puppy (and 'Live' Linuxes as well) of 2 types of operations; namely
In Frugal, a system is booted via its OS (housing) and the changes made by its user is saved in a session container we call "save". That's it, nothing more.
The housing can be an extract from the ISO/IMG OR the housing can be the 'Live' ISO/IMG file itself. Again, nothing more.
So in summary, a Frugal is the combination of its housing and its session.
In essence, either Frugals are a "LIVE" implementation! ... whether we want to see it that way or not. Booting from ISO where it finds its session, OR booting from disk (you know, the place where the contents was copied elsewhere for booting) where it finds its session is operationally the same thing.
There is sometimes a concept I have found on the forum to want to think that a Frugal is an install. In my olden days, I too felt that if I had to write something to a disk to run the computer. But, since Knoppix I learned that was NOT true. Further, I have come to know that booting from the ISO/IMG file is more secure as the base system cannot be written to.
All that said, and turning my attention to distro sessions, PSAVE parm or SAVESPEC file are EXCELLENT features of WoofCE distros. @wiak offers a similar file for KL use. This instructs the booting distro 'where' the partition is located on the PC's storage that has the session needed to complete the operational system setup as well as where to store (aka SAVE) the system's changes done by the user.
The /mnt/home, above, in my case is NOT the Session folder where the SAVESPEC/PSAVE= points to. In my case, it is showing the "partition" that contains the save-session ... not the Session 'folder' (aka /mnt/home/Sessions) which is on the partition. It is the reason I posted what occurred in my test. There is nothing wrong with the utility and I posted so that others, who may not have tested, can readily see what the default setting offers.
Your utility, which calls this backup feature, works very well. In the backup feature, we have the need to ensure we direct the backup to a location that will meet our needs. This, that you & @rcrsn51 provides are just what I like as it removes the thought process I go thru when using Grsync that I exercised in the past because to backup or restore is reduced to a button selection and/or navigational entries via the utility itself.
Thanks for the work that you 2 have done over the past weeks in bringing attention to this in the forum.
BTW: YES,there is an issue with WoofCE PUPs where it does NOT respect the SAVESPEC file when launched from Ventoy. This issue does NOT exist when launched from SG2D. I've offered to help, subtly, but no takers and the dev team are busy with other things rather than addressing the issue. I show this in my past posts so that members can gain the 'respect' for session guidance. This is done via interrupting at WoofCE's menu to add a PSAVE parm to 'force' the respect to locate the session needed to get to the operational desktop and have session-management behave the way we expect. In essence, this is limited to WoofCE PUPs. I have not found issue, booting-saving, with other forum distro's ISO files using either SG2D or Ventoy.
Thanks AGAIN for the effort you and @rcrsn51 have done to help us in Puppyland. 
P.S. I am saying this, here, as some may 'jump' because DVD booting is not mentioned. Yes, the DVD when created from its ISO/IMG is a 'housing', as well. And it, along with any session you save to its multisession existence is a self contained operational system saving the session directly on the DVD.