Nothing made of wood should ever go in the dishwasher.  Use the sink instead.

When I did some many years ago, I used WOP.  Today, I would probably use Tung Oil (probably 1:1 with limonene) - at least three coats allowing each coat to cure 8-12 hours, or longer before reapplying.

The thing about Tung Oil is that a few years down the road when it starts to look at bit tired, you can buff it lightly with steel wool and apply a fresh application to make it look brand new.  You can refinish WOP, but you would need to sand it more aggressively, and you would probably need multiple coats.  And I prefer the softer gloss of pure Tung Oil to the high gloss of WOP.

I just use mineral oil.  Hand wash and dry. reapply as needed.

If you are making multiples, likely at least some will go to households other than yours.

My experience pure tung oil takes week or more to dry.  Thinning may shorten drying time, but then thinner film/less protection.

I doubt very much typical household has tung oil or walnut oil or poly in the closet, cans once opened likely to solidify over time, limited sources to purchase.

Many households already have mineral oil in a closet, if not easy to find in any grocery store or pharmacy.  Doesn't sound as elegant as tung/poly/walnut but in my opinion more practical and efficient for customer.  Over the last ten years I have sold at least a hundred spurtles with mineral oil "finish" and haven't heard a single negative comment about mineral oil.

The walnut oil they sell at Woodcraft works well.