While I second this (I use Firefox as my main browser more or less uninterrupted since 15 years) some of what I perceive within the org worries me.

Mozilla does a lot of cool stuff aside of the browser, but what annoys me about ads in the address bar, shamelessly pushing pocket (a icon which for some reason I have to remove over and over again from the GUI) and similar things is not that they try to monetize their browser. What annoys me is that they don't have the trust in their own product that people would be willing to support them if they just asked. What annoys me is that they try those borderline dark-patterns and still try to sell it as a great feature for the user.

Just be honest to your users and if they understand your reasons they will support you, if they trust your decisions. Firefox was once a browser whos users bought T-shirts on it after all.