it just redirects all the data collection from Google to Murena

Where did you see that? My understand is that it's only the case if you explicitly create then use a Murena account.

Also trading one corporation against another, in that case if the user genuinely want to (they are not being coerced), would be technically true but... Google is not "one corp". It's one of the largest corporation ever, one of the only two popular mobile OS. It does not mean automatically picking another corporation is better but it's definitely hard to do worst.