How can I merge several databases?

"Hello,

As a newcomer to Home Assistant, I have several databases, including InfluxDB, Mariadb, and an older database from Home Assistant. I would like to merge all this data into a single database and ideally move it to a server installed on Proxmox, so that Home Assistant can store and retrieve data there.

Do you have any ideas or procedures on how I could achieve this? Thank you for your assistance!"