Does it make sense? My NC runs on a Postgres DB. On the same server I run a Wordpress installation. WP uses a MySQL DB. Would it make sense to move all data from the Postgres DB into the MySQL DB in order to run only one single DB on the server?
Or, if it would make sense to run only a single DB, would it than be better to continue running NC on Postgres, but I should move the WP data from MySQL DB into Postgres DB?
I’d prefer to manage only one database server. A few people here changed in the past to Postgres (also the VM solution: github.com/nextcloud/vm), perhaps you can find a bit of information why they did it to see the difference.
For Wordpress, we can’t tell you if it rans easily on Postgres as well. In the end, it’s often a personal preference. If you have years of experience with one type, I’d go with this solution and use test setups to gather experience with the other solution first.