Deployment is mostly-automated - put a note in our chat channel topic that you're deploying (or queue if someone else is already deploying), push a button to do a release and deploy as staging (and a small smoke test), do any manual testing (or investigation of logs etc. if something goes wrong), push another button to flip that deploy to be prod.

Any of the 12 devs can do this (and does, we each deploy our own features/stories), any of the 12 devs can make changes to the deployment scripting just like with any other code area (some will be more or less familiar with them, but that's true of any area of the codebase). Nothing unique about it, quite the opposite.