It’s also just crowd-sourced data.
Ask them for permission to use the data in OSM according to the contributor terms. You can offer to assist adding them to OSM.
If I understood right, it’s a facebook forum where people report locations which the main author adds to his personal google map.
So just provide an easy way for people to add the E85 to OSM. Probably do a youtube video showing how to sign up and then use ID to simply add this single attribute. Don’t go into detail too much about OSM. In case people are interested they’ll ask by themselves what else can be done with OSM.
Then provide a useful map with OSM. Or letz the original author do his map based on OSM. I’m quite sure he did use google because it was easy to do, not because he thought of google superior to OSM.
You could end up with a map similar so this one I created in a few minutes showing PTT stations in Thailand:
What do you mean by “too late already”?
Why should these volunteers not be introduced to contributing to OSM instead of a private map project?
They already have the mindset of crowd-sourcing geographic information. A perfect match for OSM.