If you’re comfortable with AWS or any other VPS provider, there are Ansible and Docker flavours of most common tools. I’m a fan of Jenkins but the competition also offers some well defined pathways to get this going easily, and all of them offer a somewhat similar way to define builds automatically in code. My go-to is the github org scanner plugin that can watch for new repos with a Jenkinsfile, and will happily manage creating the automatic commit hooks if a new one is found giving you a very similar level of ‘magic’ integration to what the SaaS tools offer.