No getting the option Create Pull Request in GitHub

The page displays:

main and read-from-excel are entirely different commit histories.

That means they have no common history, no common ancestor commit from which one was created from the other.
It is as if read-from-excel is an orphan branch, created with git switch --orphan.

That would explain why there is no pull request possible.

One possible option is to root rebase read-from-excel on top of main, and force push it.
Then comparing the two would include a pull request option.

git pull
git switch read-from-excel
git rebase --root main
git push --force