I have a now spare external SSD that has a fresh MacOS Catalina install

I lent a spare SSD to my brother, and his computer died. I have several Macs, and a Gaming PC in my house. This SSD has a newly fresh install of MacOS Catalina on it. He had this in an external enclosure testing out Catalina to see if he wanted to upgrade to the recent Catalina update of 10.5.4

So I'm sitting with a fresh install that was just setup this week.

My current gaming rig is a Z170 ATX Motherboard, an i7-6700k, and a Asus 1070 Strix.

In the past I have played around with Windows, and Grub to install Linux distros on my Mac.

I understand I need to either use Clover, or Open Core to use an EFI to boot up the MacOS.

I would like to have my 2TB SSD for my Windows, and then boot up this SSD for the MacOS.

Every set of instructions/video I see wants me to configure clover etc and then have that download and install MacOS.

I know I will have to get Nvidia drivers from either one of these places:

1. https://github.com/Benjamin-Dobell/nvidia-update
2. https://www.nvidia.com/download/driverResults.aspx/149652/

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Is there a way to just install Clover, or Open Core and not have to redownload and install MacOS Catalina on the SSD?