Is it possible to apply a texture from a file to a material, without converting to a .uasset?

I’m making a custom importer without using the Editor or Developer classes, and I was wondering if I can apply a texture from a file (like, .png, .jpeg, …) to a material, without making that texture a .uasset?

I couldn’t find the information for this, hence the asking. Sorry if i missed this info somewhere, still would apreciate an answer or a pin point to something that could answer this.