I searched the documentation URL with Google for the word "tenant" and it returned no results. Does this mean that Anvil does not support multitenancy, for SaaS sites?
Multi-tenant/single-DB is a pretty common and straightforward pattern with a lot of support in Anvil (eg restricted views, as described in the video).
I'm also currently working on a multi-part video series, showing the creation of a SaaS product, from scratch to monetisation. Sign up for our mailing list, and watch this space :D