I am using FaunaDB for a side project and your product would be a very good fit to work with their tech.

They have a built-in authentication in their distributed database, but not session management. A lot of people is starting to build things with FaunaDB and struggling with auth. In their Slack they even had to open a channel only for authentication doubts.

So if you are looking for a niche, the FaunaDB integration could be a good shot.