Inside Sticker Maker app, you can then import the stickers into WhatsApp
Getting stickers from WhatsApp
Method 1: Export chat (Any, recommended)
Start a note to self chat.
Send all stickers in this chat
Go to Settings > Chats > Chat history > Export chat. Make sure you choose “Include media”
Extract the zip, your stickers are “STK-*.webp”
Method 2: From Internal Storage (Android phone)
Inside “/storage/emulated/0/Whatsapp/media/Whatsapp Stickers” OR “/storage/emulated/0/Android/media/com.whatsapp/WhatsApp/Media/WhatsApp Stickers”
Note: Only stickers you received or starred gets saved to WhatsApp itself. Sticker packs on your device are stored in Sticker applications they belong to.
Method 3: WhatsApp Web (Any)
Go to WhatsApp Web, right click on sticker and click “Save image as…”
You may use this script to help: https://github.com/NoahvdAa/WhatsApp-Sticker-Exporter