Really seal it...
To really seal it, they make a sealer product for house fires. It locks in EVERYTHING. Then you can paint it any color on top of that. I used it on a rental house one time that had been neglected with cats and the pee stains went through the carpet, through the padding, and soaked into the hard wood floors. The smell was so bad that a few people actually puked when they walked in. That was over 10 years ago, and to this day you can't smell a thing. Of course, you can never go back to a finished wood look, it will always have to be painted.