Profile sync across devices

Got it. So I need to think about how profiles work differently than I initially assumed.
Does this mean that I can have only one profile per sync target? Or can I have multiple profiles to the same sync target?

I tried creating a new profile, but then used the same sync target (OneDrive) as the default profile. The new profile pulled everything down from the default. Not what I was hoping for, but if there can only be one profile/sync target pair, then this would make sense. Unfortunate, but understandable.

I use Joplin for a wide array of classwork, work, and personal reasons. I like having a streamlined set of notebooks and tags for each context. I'm not seeing how I can do that with Joplin without using multiple sync targets. Alternatively, could I use "filesystem" as a target but use the full path to a Onedrive folder?

Thank you.