:has_and_belongs_to_many or similar referring to non-SQL object

I have an ActiveRecord object called Project, which :has_and_belongs_to_many Topics. Topic used to be ActiveRecord as well, but now references a table in AWS DynamoDB. (Project is still in Postgresql.) Is there a Rails shorthand for :has_and_belongs_to_many that will work with Topic being a different type of database than the original Postgresql?