And for local dev, you can have a second docker-compose file (docker-compose-dev.yml) that has your local-specific settings in it. I have Justfile commands set up for both "just dc-up" and "just dc-up-dev"

yep, I use docker-compose for everything - even simple, single-service environments. I use the private Github app source, set to track the main branch. I check in some new code to the main branch, and get an email from Coolify a minute later to say that the new version has been built and deployed.

Not sure if that made sense, but I just went back to letting the server rebuild the images.

If your repository has a docker-compose.yml file that pointed to the image that Github Actions builds, then you can still use the Coolify Git app. BUT - then you run into a new problem: Coolify sees the change and redeploys, but that will be before the GH Action has finished building the server.