Microsoft was forced to allow browser choice in the EU. I don't see why Apple and Google shouldn't be subject to the same, with the added condition that browser rendering engine diversity gets preferential treatment.
Give users a 60% chance to see Firefox as the first option, then show them the multitude of Chrome/Safari-based browsers.
The problem is that even when that choice is given, every Google search pushes Chrome, Microsoft constantly pushes you to switch to Edge. I'm not sure how much Apple pushes Safari, but last I heard it actually gives superior battery life on Mac OS so there's a real technical reason to not use Firefox.
Because no one cares anymore about browser diversity now that the main browser is open source, runs on every platform and complies mostly with browser standards. Not to say it isn't important. But it was way worse when IE was creating a dependency on IE and Windows due to poor standards.
Give users a 60% chance to see Firefox as the first option, then show them the multitude of Chrome/Safari-based browsers.