Curious if anyone know any implementation where they would be automatically updated?

Now that would be awesome!

EDIT: come to think of it, it would require going through CDC stream, and figuring out if any of the tables affected are a dependency of given materialized view. Maybe with some ast parsing as well to handle tenants/partitions. Sounds like it can work?

MSSQL and Sybase SQLAnywhere has options for that, we use it a fair bit with both.

At least on SQLAnywhere it seems to be implemented using triggers, ie not unlike what one would do if rolling your own.