Minecraft Earth
Minecraft Earth has unfortunately been shut down. However, the game seems to save various textures to its data folder, just sitting there for the taking. While it most likely doesn't have all of the textures, if enough people contribute, we might be able to assemble a full collection.
How to rip
Go to the game's data folder using the files app if on iOS (On My iPhone > Minecraft Earth), or the /data/data/com.mojang.minecraftearth/data/ folder if on android.
You will want to go to internal > premium_cache > resource_packs, and find the folder with the most items(mine was named iXgDXrXWIwA= and had 27 items). This is probably the one you want. Check in all of the mobs > [mob type] folders, and see if you find anything.
File Formats
.png - Standard PNG Image
.tga - TGA Image