Hi,
I was mistaken about the CC-BY-SA, it seems it does not force the developer to release works based on it in the same license, even though the art would still be licensed under the CC-BY-SA and would require credits.
In the Frequently Asked Questions - Creative Commons
CC licenses do not require the collection or the compilation itself to be made available under an SA license, even though each individual work is still licensed individually under an SA license and if they were modified by the distributor the modified photo would need to be licensed under the same terms.
When reading stackoverflow, the answers are not straightforward.
The only asset that I'm giving out for commercial as a freebie is the asset pack of fantasy chiptunes. Everything else is a soundtrack that I have already produced and that is intended for listening and not for commercial use (unless permission given).
-> here, all of the mp3 are released under CC-BY-SA and not CC-BY-SA-NC (NonCommercial), so it can be used commercially, I'm not sure if you are aware.