Hi @fidoandpatch Matt,
At this time Nested collections Is only available as a Wishlist item: Nested Collection Lists | Webflow Wishlist
It is currently in the planning phase. I can say that 2020 is a year of exciting announcements. What they will be or when they will be I do not know.
You can sorta get around this by using MixItUp: [TUTORIAL] MixItUp3 - Filtering, Sorting and PAGINATION
There are also some new things coming from this in the future as well.
I wish I had better news for you but that is all I have at this time.
Best Regards,
~ Brandon