Assign Virtual Desktop to specific dual monitor?

I have 2 monitors. I’m using the Nvidia driver in Twinview Mode on the right side. I can move the cursor from one monitor to the next and I can drag applications between the two. I have multiple activities. And the second monitor selected one of those other activities as the background. I’m not sure how this was chosen, or if I have a choice. Anyone know? Do activities affect what is displayed in a dual monitor setting? As I toggle through the activities, the two monitors change, but never to the same one.

When I open an application, it’s a guessing game which monitor it appears on. Can I control that?

I know if one clicks the top left corner of an application they can send it “To Desktop” (“all”, “Desktop 1”, “Desktop 2”, etc). If I could assign “Desktop 1” to monitor 1, and “Desktop 2” to monitor 2, I could then use the “To Desktop”.

At a minimum, how does one control where applications open in a dual monitor setting?

Thank you.

This is similar to:
Different desktop on each monitor - openSUSE Forums

I don’t understand this. Twinview combines both monitors into one desktop. So regardless whether you switch activities or desktops, the same desktop/activity should appear on both monitors.
You say you are “using the Nvidia driver in Twinview Mode on the right side”. That’s impossible, full stop. My guess is therefore that you’re not running Twinview at all.