Install
This is the repository archive. It installs, but the folder name will carry the branch suffix and updates will not flow.
Install straight from GitHub with WP-CLI:
wp plugin install https://github.com/trepmal/export-one-post/archive/refs/heads/master.zipNo built-in updater. New versions won't appear under Dashboard → Updates. Install new releases yourself, or let Git Updater track the repository.
Works on pages and custom post types!
In the Block Editor, the option can be found under the kebab menu:

In the Classic Editor, the option can be found in the Publish box:

And in the row actions for quick access:

Confirmed working as of WordPress 5.4.1, single and multisite.
WP-CLI
There is a core command, this plugin is not required.
wp export --post__in=123