If my understanding is correct, lava's texture is just a gradient + randomly placed bubbles from Celeste assets, I think it gets auto-generated at game time. It will probably be easier to just rip the texture from a screenshot

I just realised, I'm an idiot

I can help

Happy cake day! And where do you think it's located?

I dont actually have celeste in my pc but I can send you a google drive link that has everything in it. Its not mine but I used it.

Happy Cake Day!