Best archival product for wood panels to oil paint on?
Wood is live material and unless you wrap it in something like hard lack deeply soaked into or acrylic resin, then it will wrap a bit here and there according to grain orientation.
So it depends on what is your tolerance and how big warp is still OK for you.
As you plan to go with oil painting, I would stick to the oils not reinventing wheel.
Lighter the oil, deeper it penetrates, and it also depends on wood in panel and its hardness.
I like natural materials so as base layers and finish I'm using various combinations of linseed oil, Tung oil, turpentine or some thinner oils to lighten suspension so it soak to wood more easily and stays deeper once turpentine vaporize out. Bees wax, is good to more final layers as it let's you polish the wood to glossy surface, but as you are going to paint on it I'd stay away from wax based things in material prep/preservation phase. Tung oil is good for finals as well as it hardens over time. Camelia oil (camellia sinensis) in contrary do not almost dry, so I use it more for tool preservation. Might be useful, but panel might catch more dust over time. Linseed is fine, but in natural form it almost don't dry and so is sticky for weeks, boiled one dries quicker, but still in days and so is used in carpentry, commercial ones usually also contain a good chunk of desiccants to make it dry even faster, but I do not like those much. For interiors I like saflor oil, does not smell, it's light, could be purchased in food grade quality for stuff like wooden kitchenware.
So my favorite would be turpentine (or some lighter oil like grape oil) + linseed (that boiled but natural one) or saflor instead of linseed.