Athos Kele has tons of materials breakdowns suitable for all kinds of projects.
Athos Kele maintains Sharpstance Youtube Channel sharing free material breakdowns on Substance Designer every week. He presents materials that look good and have an easy to read graph for education purposes. Some materials might not be optimized for use under a runtime environment as a substance, but if you bake the textures you can use them everywhere.
You are free to use shown materials in any project you like, including commercial projects. Let’s take a look at some of the breakdowns:
Embossed Rock / Gold
Sandbag / Trench Wall
The artist needs your help to keep uploading breakdowns, so if you like his work you can support him on Patreon.