Is There a Runtime Environment for Containerization?

With fly.io or these Heroku like push push services I mean life has just become easier where it's just like okay I don't want to have to set up a server because yes you have to install image magic and whatever else kind of dependencies you need. One of the biggest advantages is that you don't need a runtime right especially like build tools like this to the re and stuff. That was such a big black box for me that that was like the big one of the biggest reasons why I wanted to go towards containerization and deploying as a container right so how do you manage stuff like that? "I'm using Proxmox which is a virtualization platform the basic inspiration