Most countries have anti-monopoly agencies. Whether they are of a mind to take action or not is another question entirely. Sometimes they are absolutely toothless. I miss the days when they used to do stuff like when MS was prevented from forcing browser/search engine (I cannot remember which) by default etc.
We absolutely should try to lobby as much as we can to nudge them to act, but I don't think we can rely on government agencies alone. MS recent acquisition shows that agencies are either not motivated, or not competent enough to oppose tech giants.
I'm very security minded and email is a really tricky one. I've moved search and browser easy. I moved from Android to GrapheneOS. Email I am more reluctant because I have had it a very long time. I have been trailing Proton Mail for about 8 months now and have been very happy with this. I'm now at the place to migrate most of my activity towards it. The only hesitation I have is probably banking, which may lag behind, but it is always about taking steps on this journey. I am in a weening process ;).
It's a big and stressful transition and people will go at whatever pace they are comfortable. As long as we all work together and support each other through this journey, awesome.
I don't know enough about Proton alternatives so I am more reluctant. Proton is a combination of credible yet trustworthy that works for me, but as I say, everyone has different levels of comfort.