Is there any ability to extend the max rows/columns past the 300 rows that appears to be the limit in the UI?
We have intentionally limited the amount of cells in a Streamsheet. This is because Streamsheets are not intended to store big amounts of data, but rather for processing them.
It is always possible to use a database for storing data and use queries to access it again.
Check out e.g. our MongoDB in our documentation and learn Using MONGO.AGGREGATE in this post.
You can find out how to add these databases to your system here.
Further we are working on table widgets, which will solve this issue. But this will have to wait until a future release.