Fanatec's new Xbox One Hubs work with the PS4 too. It was weird, first they sold PS4 and Xbox One Hubs/steering wheels seperate. Then they discontinued PS4 hubs, because the Xbox One hubs worked on PS4 too. They even had the check-boxes "PC", "PS3", "PS4", "PS4" checked and green-lit. Then Sony asked them to remove the check-boxes while they are still negotiating deals with Sony. Here is the link:
http://www.fanatec.de/forum/discussion/187/playstation-compatibility
So there are products
that work with both consoles. Problem is that buying a Thrustmaster pedals, wheel-addon and two whell-bases (TX for XB1 and T300 for PS4) will still come a lot cheaper than buying the one Fanatec setup. Still, you get Fanatec quality that is worth a premium.
Jeff Gerstmann said on a recent Giant Bombcast that he asked about wheel support for Forza on PC and got the answer that wheels are not supported in Apex, but they will look into DX12 input integration, so it might come later on or at least in the next Forza that will come to PC as a full (and full priced) game in fall.