A GIGABYTE Z490 Vision D build with both NVIDIA and ATI GPUs?

Looking to build a hackintosh using the Gigabyte Z490 Vision D motherboard (with an i7-1070 processor) as it supports thunderbolt 3 and seems to have a few success stories. I would like to continue to boot into Windows 10 for gaming however, and I have an NVIDIA 2080TI that I would like to keep using. So I would like to have the NVIDIA card in the primary X16 slot and purchase an ATI card for the secondary X8 slot. This will bring the primary card down to X8 bandwidth, but I understand that shouldn't result in a significant performance hit.

1. Can I disable the Nvidia card for the purposes of using MacOS (preferably automically via software or alternatively manually through the BIOS)- I've read conflicting information on this. Can anyone with this mobo confirm one of the methods described here works well?
2. Is there a different motherboard that would accommodate dual booting with ATI and Nvidia cards better?