Divvy for window management (assign your own shortcut).

For almost everything else there's a standardized system-wide shortcut (including the ancient ones like Ctrl+a/e for text).

If there isn't a shortcut, but the app exposes the action in a menu, you can assign a custom shortcut from keyboard settings.

MacOS has traditionally been very friendly to keyboard navigation. Well, until somewhat recently when mobile-only/mobile-first devs started just slapping Catalyst on and calling it a day. Even Apple's own apps suffer from this.