I just want to know if it is possible to see Custom Armor Models with EMF and this mod

Most likely, it will appear black because, although emf uses the vanilla rendering models, it does not use the default path for its textures, but rather a custom one. Therefore, when my mod renders it, it will not find it and it will appear black or black and purple.

Ideally, the EMF developers would make their mod compatible with mine when they have some free time. If they haven't done so, I will probably make it compatible myself and send a pull request to the EMF repository.

As I mentioned in other comments, compatibility with EMF depends completely on its developer. I already created a comment in its repository about it, mentioning that they asked for it and how to do it. The only thing left is for him to implement it and if they want it so much, go to my comment in his repository and give him support so that the EMF dev sees that they really ask for said feature.

I'm testing a new implementation for 1.21.9+ in which all mods and resource packs should be compatible. If it works correctly, I'll try to backport to previous versions.