Insert saved signature in Pages.app
I couldn't find any solution for a similar shortcut, and I ended using:


"Capture screen" any white and small space from the screen.
Open the "Captured picture" with the Preview app.
Add your signature to the "Captured picture".
Add the "Captured picture" with your signature to the page document.


Here is a video about the short trick:

https://www.youtube.com/watch?v=VSEQeQ-8kNI