Well... Its not something I recommend! It’s a lot of work and depending on the keyboard layout & keys you might not find the needed part as they are hard to come by as Apple has made it hard.
To give you an idea on what it takes review this older Early 2013 13” MacBook Pro [https://www.youtube.com/watch?v=W1Purem1NF0|Apple Really Doesn’t Want You To Fix This - MacBook Keyboard Replacement] getting the battery out and the keyboard backlight plate is a bit more complex.
In the end you’ll likely need to replace the battery and you may end up damaging the backlight plate.
In the end it just cheaper and easier replacing the full upper case assembly. You can thank Apple making it so hard needlessly and expensive to boot!