Ok I didn’t want to post this until I was able to secure pictures! My dad’s old house in Connecticut had original floors that he kept when he and my mom removed them during a renovation of the house in the 70s. He brought the wood down here to Texas when he got transferred and has used it for various woodworking projects over the years. He has always called it southern yellow pine, it is very hard and dense. A few years ago, he asked me about using it to make a new handle on a knife. Here is the result:

It looks shiny because I stabilized it with epoxy so it would hold up better when left wet in the sink.

I made this several years ago, as you can see it is holding up well!!
Yes the wood will have nail holes, but for a knife handle you don’t need a wide piece and I am sure you can get lots of working chunks off the door. Have fun, and feel free to PM me if you have questions (though I am FAR from an expert)!