First of all, I consider it rather ignorant to answer a 10-bit related question with "it's not HDR/EDR" compatible. Those are two different things.
I also have a 10-bit compatible setup (Quadro K2200, DELL U2711) and despite the whole 32bit workflow compatiblity of Affinity I have yet to see if that's true. There is no setting to be found. Then there is this answer from a forum admin telling me I need to activate AERO interface on my win7 desktop (fun fact, with Photoshop you need to disable that) and still ... brushes are banding all over the place, no matter the settings.
I run the 1.8.3 version and have all the latest stable drivers and I am running a i7-4790K @4GHz with 32GByte RAM. More than enough to edit 25 layers of 2k*5k pixels in 30 bit workflow without even stressing out my PC. That is, in photoshop.
So long story short: how does Affinity support 30-bit workflow (not HDR, not EDR... but 30-bit) and how can a user check and/or enable this?