World generation, remove lava and ice, (1.21.4)

Hi,
I am new to data packs, I have some coding experience from other stuff, so I understand some of it, but.
I want to make a data pack that changes the world generation to be basically just void, with biomes and some structures generating, (I have gotten the structures I want, and biomes are still appearing correctly). I have tried to make the rest void, and gotten most of it, but there is still lava in the bottom of the world and in frozen ocean biomes there is still big pieces of packed ice.
Do anyone know how to get the data pack to not generate those things (ice and lava), or are able to figure it out?
And I would like it to be in the latest version of Minecraft.
(Image is showing what I want to remove)
I have tried for a few days now, so any help is appreciated.
Link to current version: https://github.com/sekaberg/OneBlock
This tool has been to a huge help for me: https://misode.github.io/
Thanks