Is it allowed to make ERA-compatible files for free distribution (e.g. in GitHub or the Vault) out of Guild Companion's articles? Particularly interesting ones would be e.g. new professions and spell lists, but also races and cultures.
The articles are mostly OGL, so under that license I believe files like this would count as derivative works, if not even redistributed works, and so I believe they would be allowed. However, as it happens, it's prudent to ask first.