I have no experience with Synology but I can give you some pointers on how to sync to PC and you can take it from there:
-
This method uses A-Shell instead of iSH, but I think iSH could work (I quite forgot what issues might be lurking there if any, alas – you need to look it up).
Neither iSH nor A-Shell needs a JB device. - In this post I mention using a method that sort of started out as and then stopped involving
rsync
(I did not needrclone
) (not sure how fast that would be, I only use it for small updates of tiny folders) but needs a jailbroken device to access the vault with a symlink.