How to overlay a gif-animation of the screen on an iPhone mockup (png)?

Question

Design

Maybe you have come across: how to make a gif of a static background of an iPhone mockup with animation inside?
Like here in the center (but not using css)
project150396.tilda.ws/iphone-gif

Answer 1

Can be done in Principle or After Effects.

Answer 2

Online mockup generator pictofon.com can insert gif-animation into static mockups: