How do I publish only one page to production after making changes on staging?

No, not unless you push the change manually.

More specifically, WordPress has no concept of production/preprod/etc or of pushing/pulling. These features are always implemented by hosts or custom software, and are extensions of WP, not parts of WP itself.

Otherwise, production and preprod etc are just 2 separate WP installations that just happen to be very similar and run similar code.

If you want to migrate changes in a post on preprod to production, you can do that manually. Open the post up on the target environment, and retrace your steps to redo the changes you wanted. You can open both side by side and compare, and copy/paste things. As mentioned before, WP has no concept of push or pull content, there is no built in tool for what you seek.

Alternatively your host may have a solution for this in their staging/preprod/production feature, but most do not. You would need to ask your host about that. There may also be plugins that assist in this out there. I don’t know of any, and plugin recommendations aren’t in the scope of this stack anyway