I'm building and deploying appbundle from my self hosted runner for this exact reason.

I manually maintain flutter and Android sdk on my server.

I've never been a docker fan, I prefer to completely handle my whole stack.

I have scripts to install the required tools and some actions in my scripts are just echoing what needs to be done manually.

With the years, I've found that infra for fully reproducible builds cost too much to maintain for us.