Epoxy resin-based products make excellent primers, sealers, or bases for many topcoat finishes. After the product is properly cured and sanded, many finishes can be applied over the top. The epoxy presents a "friendly" surface and makes it easy for many finishes to flow out and adhere very well.
2-part polyurethane (solvent or waterborne)
*Usually compatible but should be tested prior to application on your project.
With all these choices available, your project can be well-sealed, even waterproof, and come out beautiful just the way you intended.