The EU should fork firefox and develop it as a public benefit
What the union should do instead is to create a funding structure that had as it's mission to identify and financially support groups that develop open source software which is critical to both the people and companies that are based in the EU. Make it a requirement that the software be accessible, free and open source.
All these mega-rich US tech entrepreneurs can finance Firefox development. They have all the capital. The EU isn't a charity.