I couldn't speak to separate physical machines, but I run several "servers" as part of my dev environment.

You'd have to ensure that their ports and data directories don't collide, but I don't think you'll have a problem having "process-compose up" start multiple separate mysql, postgres, or webserver instances.

I just dedicate a terminal pane to it so I can arrow around and see the logs and health status of my databases (plus things like Prometheus and Grafana, I like to be able to nuke the cluster and have everything flatline, rather than having telemetry itself die when k8s goes away).

Both mysql and postgres are included in https://github.com/juspay/services-flake which you might find interesting.