I think the commands are:

git checkout production

git rebase main

that gets everything from main into production.

Yes, but rebase is like rebranch. So you take a branch from a tree, and plant it on top of a new tree. So, you rebranch (rebase) production branch on top of the main branch.

git rebase (current branch onto) main

This would rewrite the history for production. Not what you want to do

The point, as I understand it, is that production has no meaningful history separate from main's history: it acts as a bare pointer, and rebasing it just fast-forwards it to later points in main's history.