Should my polyurethane sheen and paint sheen match?
Same sheen is a safe route, but it’s all just opinions and a question of style. Personally, I’d say use a semi-gloss paint on the legs — it’s more washable than satin paint and the difference in reflection isn’t much if any because the planes that’ll reflect light at any point are small compared to the table top. Just do a good paint/poly job and don’t use flat paint unless you want that “shabby chic” or a dirty/rustic look.