Some Apps Appear in Mission Control but Not in the Application Switcher
Only applications that are present in the Dock are shown in the Switcher (⌘ cmd+⇥ tab). More specifically the apps that do not have the LSUIElement key in their Info.plist.

Theoretically you can remove that key from the apps, that you want to see in the Switcher, but this can break the Code Signing.

The examples you've shown are not even the apps, but Panels (NSPanel). They are part of the app that is in focus (when you click on them, the current app in the menu does not change).

3rd party app switchers are discussed there on AskDifferent.

If you want to check if a window is a Panel, you can use Accessibility Inspector app like so: