There is no "Google Docs" format, though - you have no idea how Google is representing your data, or if there even is any single "blob" that is your file (and even if there is one on the server side, AFAIK you can't get it). I'm not very familiar with Notion, but it seems like it's probably the same way. That means there's no chance of "Google Docs" or "Notion" becoming a standardized format. At least with a proprietary standalone format you (or the community) has a chance at reverse engineering it.