Any lightly white washed finish will keep it close to the raw wood look. Ceramic star in ultra matte is a good quality finish ., Bna traffic HD extra matte or Loba Supra AT.

Thanks so much sorry just to clarify - these finishes have a white washed effect?

To anyone who's pondering it, DO NOT try any product with white tint on Walnut. Learn from my mistake.

I doubt you're looking for the popular raw wood look and suspect you want to bring back the rich warm brown natural tones. The best options would be to use a sealer like DuraSeal or Bona Neutral, followed by something like Bona Traffic Matte. Another option is to use a Bona sealer like AmberSeal or IntenseSeal before the Traffic. I don't believe that any of these products have UV filters so the wood will again be affected by light, especially direct sunlight.

My flooring contractor wants to use Loba hybrid. Im concerned that it will yellow like the old oil.

Hybrid ihas slight yellowing, nothing special. I don't believe it is available in matte. So, you will still need to select a matte finish if, that is what you want. Cheaper to use Easy Primer with amberizer and top it with Supra AT. Hybrid is a low/mid quality finish. I don't waste my time with it. Supra isn't going to cost that much more per gallon., then you have Supra AT. Walnut is soft anyways, put a hiigh quality hard finish on it.

Unlike most woods that deepen in color, Walnut naturally FADES to an amber tone. That is 100% inside the wood, and a natural property of the wood. The only way to keep it a deep rich brown is to stain it.