If in doubt, try it out. Sanding sealer on a scrap piece of wood, then try the poly over the top. There are various types of sanding sealer, so I expect not all will work well with poly, but most should.
Any gloss finish, be it nitro, poly, acrylic etc. rellys on being able to get the final surface really flat. You can just apply lots of coats of the final coat, so it’s deep enough to fill all the grain and have enough finish height over the wood to sand down all the ripples so it is smooth and can be polished.
But using the final coat like this is normally the most expensive and slowest way to to it. It’s much better to get the wood surface as flat and level as possible, then grain fill (depending on the wood) then sanding sealer (to help get the surface flatter as almost all grain filler shrinks a bit), so that you can minimise the number of final finish coats required.