I tried to search around the repository and didn't find any textures and models related license.

I would like to use these assets to make an open source porting of this mod to another Minecraft inspired game.

This covers the whole project. https://github.com/Geforce132/SecurityCraft/blob/1.17.1/LICENSE

Someone else made a Minecraft: Bedrock Edition port of the mod, and this is what our texture artist said in regards to using his assets:

Thank you very much!
That will help me a lot!