Add secondary GT710 after upgrade to RTX3090?

Hi! I've recently updated my GPU to RTX3090, which is of course not supported in Mac OS. Previously I had Maxwell and used webDrivers in HighSierra. I have dual boot, mostly use Windows and keep Mac OS for i.e. iphone maintenance. Therefore I thought that I can deal with no acceleration in short sessions. However, no drivers support means also that I can not change resolution from 1024x768 to needed 2560x1440 and that is a real pain. I have no GPU in CPU, to make Mac OS work I have to add supported card. I have space for single slot card. I'm thinking on MSI GT710 DDR3 (since it does not have ugly VGA cable). Therefore few questions:

1. Does somebody use two different cards from Nvidia in Windows and can confirm there is no problem with priority in apps?
2. Does this G710 is really fully supported in Big Sur?
3. Is there any way to set proper resolution in Mac OS and RTX3090? I can live without HW acceleration for my needs.

https://preview.redd.it/bav33kn8h3e61.jpg?width=617&format=pjpg&auto=webp&s=adc0dcf2fc2f541289f5da472b26a96e7a80b179