Lemon oil will make wood shiny and lasts a week. Tung oil is used by furniture professionals on wood. Most finishes will darken the wood, so you test on an inconspicuous spot. Epifanes is a marine varnish used for exterior woods.
If you have to use a varnish and don't want to darken, or have VOCs off-gassing, use a water-based polyurethane. That'll darken less than an oil-based poly.
Old antique wood furniture might have wax, like Minwax paste finishing wax. That won't dry out the wood, but gives it a long-lasting shine.
Me, I'm not going to use anything.