I’ve noticed a lot of entrepreneurs have those kinds of ambitions but nobody is hiring at the scale of WeChat (well, Tencent Holding). You’re talking about a platform/ecosystem that has tens of thousands of developers actively working on it. Twitter is in the opposite position having been cut down to the bone. Not going to happen.
Tecent already had a diversified Internet business before they launched WeChat. Musk needs a whole portofolio of companies to enable his mega-app vision, and that is not considering all the anti-competition lawsuits coming his way should he acquire those companies and refer to them exclusively within the X app.
FB/Meta and Google likely had similar ambitions and they haven't succeeded in building one despite being in a far better position to do so. Google Maps is probably the closest thing we can get to a mega-app in the Western world, for now.