How to make animated stickers in Signal?

I tried to make my own custom animated stickers but after finishing it, I was really sad it wasn’t animated, The format i was using was Webp as i got these stickers from the Whatsapp stickers’ folder, Could you help me?

Animated stickers need to first be converted to APNG before being uploaded on Signal-desktop. It’s the only animated format supported:

Is there an offline converter for APNG format?