I don't know if this is exactly what you're looking for but from the diesel docs, I believe you can init a connection using diesel::mysql, diesel::pg, and diesel::sqlite. I believe from there you can simply access an existing database, say one initialized in a container and connect to it. I dont think you would have to use the standard diesel sql scripts or migrations and could use any database with appropriate credentials from there. Sorry if I misinterpreted what you meant, however.

edit: The other option could be to go with the crates that only handle the collection and statements/queries of databases (ie: mysql crate or postgres crate). If you wanted to do something like crud operations you could use something like axum or actix for the routing and methods and have the link to the database level with those crate connections

This is so true, I use copilot for things like actions and dockerfiles so I don't feel an urge to bash my brains out more than I use it for code gen

Nowhere near as experienced as some of the users here, but I use Rust and databases on a daily basis for work. Would be willing to learn if there is a need