It’s not too hard. The most important things are web search and email. I still use Google Maps. But I don’t want my private emails and searches at a company who is user hostile and preditory.
I quite disagree, it is very hard. Sure, switching search engine takes all of two seconds, and email can be had from many vendors free and commercial.
But calendaring! A calendar that is at least somewhat integrated with am email client, supports more than one actual calendar, and has real-world capability to share them with others - “if you succeed in this, two me how.”