What's the DBMS? We moved in the other direction with postgres, merged multiple databases to simply have a schema per service/application instead. All the advantages with none of the disadvantages, imo. (We then had a single database per running test/dev environment, rather than multiple.) Of course, that's a pg thing, if you use MySQL for example it's not an option.
i think this is aligned with the author's choice. a separate schema is effectively a separate database (from a product eng perspective) with shared infra.
Yes, we are using postgres and my plan was to use separate schemas, if going the single db route.
The only thing that worried me is that one product might need SOC 2 sooner than another. I thought separate databases would give a smaller compliance surface to worry about. However, this will be my first time going through this process, so I am pretty uninformed here.