It will work with non-EE native tables as well. You can also use EE models inside of an addon to access those
I confirm this also works for non-EE tables. But for security reasons its only for SELECT queries. Which is still great for templates as no PHP is required.
I was looking at the EE Models that can also fetch data, and they can also save. But EE models are probably limited to only EE data. I was looking at saving data to my own created tables.