ifixit sells just the keyboards, why doesn't that work?
https://www.ifixit.com/products/macbook-pro-14-a2442-a2779-a...
The article is ten paragraphs (two of which are four words or shorter). The entire sixth paragraph is dedicated to answering that question.
I don't see a replacement guide link on that page, but curiously there's this note:
> The aluminum upper case and installation screws are not included.
I would assume you likely need those too, as the article also mentions.