I'm gonna wait for Steam version
Free work is ok if it's not-commercical project, such as modding for game. If it's commercical and they're going to make money off your work then it's unfair.
Daniel Thiger has released his Concrete Pack of 3 Substance materials, which can be used for all kinds of urban scenes.
The packs includes organized full source .sbs (& sbsar) files with comments.
1. Damaged Concrete Wall
2. Seattle Sidewalk
3. Concrete Rubble
Personal, Indie, and Studio Licenses are available. Substances and exported textures cannot be redistributed or resold unless as embedded components of electronic/interactive media.
Substance Designer 2017.2.2 or newer is required. Substance Player for sbsar file.