Working with Aiven to connect PostgreSQL and mySQL?

Hello to you all!

I have been using PostgreSQL to organize my data since I can remember. But since I’m not completely satisfied with the functions, I’ve been thinking about switching to mySQL for a while.
What are the advantages of MySQL compared to other databases?

I would also like to connect my databases to save myself work. I have heard that the provider Aiven should make this possible. Have you ever worked with Aiven for mySQL and can you tell me about your experiences?

I would be very grateful!