Samung Note 9: How easy is it to replace buttons

How hard is it to replace the exterior bixby and power buttons on the Note 9? Mine have broken off and now I need to use my finger nail or a small flat head to use them in any capacity. If it's as easy as replacing the entire button daughter boards, I'll just do that at the same time as replacing the battery. Also by opening the phone and doing said repairs and using the ifixit glue repair parts will the phone still be water resistant?

Edit:

If it isn't clear I'm referring to the external plastic buttons. It appears that the plastic on the inside that held them in place sheared off.