any way to not click on a window to activate it when using a 2nd monitor?

You're welcome.

Command-Tab is the fastest way to move from app to app regardless of their desktop location.

Command-Grave accent (`) will move focus from window to window in the same app on the same desktop.

You might explore the details of using System Settings > Keyboard > Keyboard Shortcuts... > Mission Control to quickly move between desktops on multiple monitors.

Work in multiple spaces on Mac - Apple Support

Also see: Mac keyboard shortcuts - Apple Support

Switching from one app to another on the Mac:

Move and arrange app windows on Mac - Apple Support

❝On your Mac, do any of the following:

• Switch to the previous app: Press Command-Tab.
• Scroll through all open apps: Press and hold the Command key, press the Tab key, then press the Left or Right arrow key until you get to the app you want. Release the Command key.
• If you change your mind while scrolling through the apps and don’t want to switch apps, press Esc (Escape) or the Period key, then release the Command key. ❞