Well I am like 1000 percent sure this would be really difficult to implement i would love a 3d blend tree similar to unity’s, i would really like to make a 3D full body shooter game however making a ton of animations for each direction a player can go in is time consuming and possibly not worth it, so if i was able to blend a left and a forward walk animation into a diagonal smoothly i would. although i know that the 3d in gdevelop is still in its baby stages this would be a huge step that would be useful for everyone i think.
Hey GrilledCheeseSandwic,
Thank you for your post and welcome to the GDevelop forum. 
Can I request you to go to ⭐ Welcome to the User Feedback channel! and read the rules of the Feature request forum and write what your issue is once again?
From the first message it was hard to understand the root of your request (so we can tag it accordingly).
Thank you.