What are the necessities to set a mounted Time Machine-created sparsebundle as a backup vacation spot in Sequoia?

My objective is to create a Sequoia Time Machine SMB backup goal which I also can mount on the backed up macOS in query (utilizing USB). I have to be capable of affirm that Time Machine will settle for the domestically mounted sparsebundle as a backup goal, ideally earlier than investing time in a big preliminary backup (I am unable to wait hours for an preliminary backup each time throughout trial-and-error). My efforts finish in tmutil giving an error 45.

Technique

1. I let Sequoia’s Time Machine create a sparsebundle on an exterior SMB
   share
2. I let Time Machine begin the precise information switch earlier than I skip the
   first backup, to make sure that the sparsebundle is totally created, with out truly having to attend for a complete full backup
3. I mount the file system that acted as host for the SMB share — which resides on USB storage and which helps UNIX file permissions — on the macOS Sequoia occasion that created the Time Machine sparsebundle
4. The sparsebundle has proprietor and group 1000:1000, i.e. the SMB person on the exterior SMB server. I can mount this sparsebundle with person 501 (my admin account). There is not a person 1000 on this method.
5. At this level tmutil setdestination -a /path/to/my/sparsebundle will complain with Permission denied, so I chown -R 501:0 the sparsebundle, and mount it once more.
6. Now tmutil setdestination will as a substitute report The operation couldn’t be accomplished. Operation not supported (error 45) The backup vacation spot couldn't be added.

At that time I am unsure what the issue is.

Query

How can I make sure that a sparsebundle (APFS) created by me through Time Machine, over SMB, can be mounted domestically and be accepted as a backup vacation spot? I’ve accomplished it earlier than with HFS+ bundles on Mojave, and I’ve accomplished it earlier than with APFS bundles on Ventura, so I am pretty assured it needs to be doable by some means.

Experiments

I’ve tried numerous experiments to see what the factors are for…

• Being allowed to mount the sparsebundle (I apparently do not should be the proprietor for this, as demonstrated by mounting it whereas being owned by 1000, however after I change the proprietor to a person that truly exists on the system (e.g. 503) then I am out of the blue not allowed to mount it…)
• Having the sparsebundle being mounted as writeable, as reported by Finder’s standing bar (have not succeeded but, however this does not even appear to be required to ensure that Time Machine to truly begin utilizing it, which I found by inspecting a mounted and dealing TM-bundle on Ventura)
• Including it as a backup vacation spot utilizing tmutil

I am nonetheless at a loss as to what precisely Time Machine needs. Different UNIX permissions? ACL magic? Some .plist entry?

Listed here are the permissions of the sparsebundle, and as you possibly can see the recursive possession of 501:0 has taken place, and it is read-writeable:

$ ls -haln bundle-name.sparsebundle 
complete 156
drwxrwxr-x@ 4 501  0    12B 12 Feb 21:00 .
drwxr-xr-x  3 501  0     4B 12 Feb 20:52 ..
-rw-rw-r--@ 1 501  0   6,0K 12 Feb 20:44 .DS_Store
-rw-rw-r--@ 1 501  0   575B 13 Feb 17:44 Data.bckup
-rw-rw-r--@ 1 501  0   575B 13 Feb 17:44 Data.plist
drwxrwxr-x@ 2 501  0    13B 13 Feb 04:07 bands
-rw-rw-r--@ 1 501  0   516B 12 Feb 20:52 com.apple.TimeMachine.MachineID.plist
-rw-rw-r--@ 1 501  0   502B 12 Feb 21:00 com.apple.TimeMachine.Outcomes.plist
-rw-rw-r--@ 1 501  0   220B 12 Feb 20:53 com.apple.TimeMachine.SnapshotHistory.plist
-rw-rw-r--@ 1 501  0     0B 12 Feb 20:44 lock
drwxrwxr-x@ 2 501  0    13B 13 Feb 04:07 mapped
-rw-rw-r--@ 1 501  0     0B 12 Feb 20:44 token

I am lacking one thing.

Extra experiments

• I’ve tried tmutil inheritbackup however it says my machine already owns the sparsebundle, which is correctly.
• I additionally tried taking a look at a working sparsebundle setup on a unique macOS (Ventura) set up, however it was nonetheless complicated. For instance: after I added write permissions for myself solely to the basis sparsebundle listing utilizing Finder’s Data dialog, and mounted it by double-clicking, then I might not again as much as it (TM complained it was now “write protected”). As quickly as I eliminated that purely extra write permission I used to be as soon as once more allowed to again as much as the bundle. That individual sparsebundle had a unique UNIX file proprietor than me.

Associated

• Earlier query that resulted within the conclusion that the bundle’s host quantity should be writeable (i.e. use a driver with write assist) simply to be restored from. That is not relevant on this case since I am attempting to do extra than simply restore, and since the host FS already is writeable. Additionally, that was earlier than Apple migrated from HFS+ to APFS for Time Machine locations, which has undoubtedly launched new necessities.