How do I add a new app, that is not already a choosable widget on the Lock Screen?

Hello Chritizin1996,

If you want to add widgets to the Lock Screen of your device, please check out the "How to add widgets to your Lock Screen" part of the link you came from, which outlines the requirements and process to do that, and may help: How to add and edit widgets on your iPhone

How to add widgets to your Lock Screen

With iOS 16, you can add widgets to your Lock Screen to get information at a glance — for example, the temperature, air quality, battery level, or upcoming calendar events.

1. Touch and hold the Lock Screen until the Customize button appears, then tap Customize.

2. Tap the box above or below the time to see the widgets that you can add to your Lock Screen.

3. Tap or drag the widgets that you want to add.

4. Tap Done.

If there’s not enough room for a new widget, you can tap the Remove button  to remove a widget and make room for the one you want to add.

Thanks!