What software will you use to write the ISO in a way to be bootable?
I, personally, am not sure Which Drive, given the name "/dev/nvme0n1" you provide, is the Empty Drive awaiting Zorin - So, I cannot say whether that is where you should proceed. I am not examining your machine there so... As you say, you Do Not Want to mess up the machine you use for Work. So Please triple check the drive and make absolute certain you are choosing the correct one (in fact, I think this is why the guide you were linked to early on even disconnected the other drive with Windows on it.)
This procedure was if you had disconnected the Windows Loaded drive. Then installed Zorin on the empty drive. Then reconnected the Windows drive and booted into Zorin first.
If the Windows drive is connected throughout, I am honestly uncertain of the proper steps. Once I did away with Windows, I never went back. So I have zero experience of dual booting a Linux Distro and Windows on the same machine.
The Last thing I would want is to provide you with misinformation that causes you grief.
I am sorry that I am not knowledgeable enough to help you. But what I can advise is the following:
-Choose Zorin Lite. Trust me on this.
-Be certain and confident in each step. Even if that means being patient and checking with many resources and knowledgeable people. Visit more than one forum. Check on AskUbuntu or anywhere else that you feel you can get Good Sage Advice.
-Make backups. Even in the best circumstances with all the proper procedures, a hardware failure at a really bad time can still rear its head and bite. Before making any changes, back up a System Restore.
I believe that you are doing the right thing by seeking confirmation each step of the way and making sure that you doing the Job Correctly. Once Zorin is installed, I can probably help you plenty. I can help much in installing Zorin alongside another distro or by itself. But Dual Boot with Windows is probably my Weakest point. I think I need to study up on that topic.