I'm running PS of a Windows 10 desktop. I have two users, my wife and myself. Can we each maintain independent libraries, etc. E.g. can my wife start PS and do a new and independent Import from what I've done?
A subsidiary question is syncing. Can we each synch for other decides independently, or does only one of us have that option?
You and your wife can work on two different catalog while being on different users.
As per the process of syncing with other devices, you can only sync one catalog at a time and in case if you switch syncing the catalog then it will wipe out all the collections on mobile from old catalog and sync the one you have in other catalog as it is catalog dependent
All that is necessary is for your wife to create a new catalog. She can import images and do her work completely independently from what you are doing. If you are talking about synchronizing with Lightroom Mobile, Lightroom Mobile can only be synchronized to one catalog. If you are talking about using each other's catalog, the answer is no, unless you allow each other into the catalog while you're not using it. The catalog is a database, and is not designed for use in a multiuser environment.