There is a type of union that is "self-aligning".
Instead of the union mating surfaces being flat and parallel, there is a ball and socket type joint with an o-ring that allows for some axial misalignment.
My previous owner had the pump (Superpump) and filter replaced and there is one of these self-aligning unions at the pump suction to account for the sloppy install in making up to the original skimmer and main drain 3-way. I think in my case they were asking it to do too much as I have always had problems with air leaks. I just dismantled, cleaned, lubed and reassembled to try to stop the air leak and now it's worse. I will be doing some replumbing myself.
I haven't found much detail online. Hayward has an assembly for a different type of installation that comes with an elbow. I do know that the "hand nut"(?) part is much wider than a regular union.