I would like to submit that making the open source version compatible with the closed source API might be an asset.

By being compatible, users get all the benefits of the existing corpus of help on the internet. And being compatible make the cost to entry lower. If somebody wants to make a very small modification of the MAC layer, they can do it as with the closed source and just go behind the curtain and file a little the thing they want to hack, without the cognitive load of learning a new API.

Author here; see also the entire series of posts on https://esp32-open-mac.be/