Sometimes the only way to answer a question is to answer it yourself @koloe. There is a philosophical concept called “enlightened self-interest” that maybe you have heard of: for those that haven’t, it means when we do good for others, we ultimately serve our own interests.
You have already identified the bigger issue problem: And that is how do we help users of WhatsApp transition to the /e/ eco-system? Moving people from what they are used to and familiar with to the unknown is hard work- especially if the technological tools don’t yet exist! 
However, if you get WhatsApp to work with MicroG and /e/ and share with the /e/ dev team what you’ve done and how you solved the problem, you will not only have fixed your own problem but also be a “hero” to those who need that functionality. The solutions you “create” may one day be incorporated into the /e/OS. And if it doesn’t currently work, perhaps communicating with the MicroG team about what you’ve done to solve the issue will help them figure out where to look so that they may be able to add this functionality.
No problem on earth is ever too large that cannot be fixed by the boundless nature of the human mind. In that sense, even if you fail in the short term with this particular goal if your work contributes to helping others feel more comfortable with making the transition to /e/, you will have helped many countless people that you will never meet IRL- And that “good” ends up rippling forever into the universe.
