So, I was able to get data from MongoDB collections pulled into datasets, and written back to datasets as well. A little scripting was required. I packaged it all up and attached it to this post. Feel free to play around with it if you'd like.
There's 1 window and 1 script module to make this all work. And, of course, make sure you grab the MongoDB module as well.
MongoDB Module: MongoDBDriver.modl
Note: There aren't any performance optimizations to this code. Certainly, if you're thinking about using this in production, make sure to do a thorough code review and adjust it to act the way you need for your organization.
Ignition: 7.5 (7.5.3)