Dual booting installation using 2 different HDDs

I have two HDDs, one with Windows 10 (the OS, program files, etc)
on the second (HDD2) I have some photos, videos, documents etc. (500 GB each)

Now I am looking to use the second one for Ubuntu only, and the first as Win10 only.

What’s the best way to do this?

Should I move all the files from the second drive to the Win10 drive and partition the whole drive as ‘free space’, disconnect the Win10 drive, install clean Ubuntu on the second one?

I would assume it would work, but when I would connect the 2 HDD, the Win10 one would ‘think’ that the second HDD is just some data and could corrupt it?

As much as possible I want Win10/Ubuntu to be separate.

I looked at a bunch of video tutorials but could not find a thorough one. Also tried looking on Ask Ubuntu but could not find. If there are any I would love to know.