Since I don’t know much about this, I’d like to know if I can use Xano to store only a certain portion of the data (like user photos and messages) and create relationships with the Adalo database to properly link the photos or messages to the users?
You can store some data in Xano and some in Adalo, but there is no built-in way to create the relationships between the two; you will need to maintain relationships manually using some field (e.g. id). In your case you can add Xano tables as External Collections.