yeah you probably read something related to how the engine itself is not open source, but you can still host all the files used to make a game on github as demonstrated in this (not the best) tutorial:
Licensing also matters, just cause it's on github doesn't mean it has an open source license, it just means it is 'source available' which is technically what I'm asking for.
So here is the updated information about open-sourcing game built in unreal, So if you have used any Epic assets from the marketplace or from any other source which you don't have the rights , then you are not meant to grant a free license to those, and instead you can leave a link to those assets in the source