What's sold as "wood conditioner" is also called "pre-stain conditioner" as mentioned in a Comment on a previous Question, and as the second name better implies they're intended to reduce/prevent blotching in blotch-prone woods when staining.
You're not staining, so no need for 'conditioning' the wood beforehand.
Also important to understand what "wood conditioners" are made from. Almost all are just a very dilute finish, e.g. thinned varnish*. So there's literally no difference to what one will do to the wood versus applying a normal polyurethane.
"Tung Oil Finish" can itself be used to 'condition' wood, so again no benefit to be gained by pre-sealing the wood beforehand with something else.
*Obviously this is something the manufacturers don't want buyers to know since some will have the bright idea that they can make the same thing themselves by thinning some varnish and using that instead. And they're right, because that's exactly what was done in the past for this purpose, see closing comment here.