First post here, if this place isn't for tech support, I'll remove it.
I’ve heard dual booting Linux and Windows isn’t a good idea because Windows Update will nuke the Linux boot loader, so I’ve avoided doing that.
For a very long, technical, and complicated reason, I still need Windows because one piece of software that I absolutely MUST have is only compatible with Windows. No, there is no alternative software available for my use case; none, zero, not any, at all. I’ve already tried running it within many different VMs, using many different hypervisors, and I’ve already tried Wine; they aren’t an option, the software isn’t stable in those cases. I don’t want to get in the weeds about it, so please just accept that I NEED some version of Windows installed.
Since Windows 10 doesn’t receive updates anymore, can I dual boot Linux and Windows 10 without worrying about whether Windows Update will break anything?
I intend to keep Windows on one drive and Linux on another. Windows would only be used when I need to run this one specific program, which is maybe five or ten hours per week. The rest of the time, I’d be using Linux.
So as your on separate drives, you shouldn't see issues with MS nuking the boot partition.
IF you are installing both from Scratch. Install Windows first. The reason for this is Windows will see the Boot partition on the 2nd disk for Linux and go "mine now". If you already have windows running (sounds like you do) then you are all set to just install Linux on the 2nd drive.
In the BIOS, Linux is the boot drive as Grub will see Windows and you can select the Distro to boot each time. I don't trust the windows selector
I also dual boot on the main PC so my wife can do her own thing. I've never had any issues with the installations on seperate disks, so you are doing the best possible setup here for this