I hear good things about Proton, but you are still sticking yourself into an ecosystem.
For documents, if you are even slightly techie, hosting your own OwnCloud/NextCloud is pretty easy. It just works. Both also offer a central calendar function, if that is important.
For email, buy your own domain, and host it with a local provider.
All the other things he mentions (to-do lists, password manager, etc.) just pick your favorite app, and store the data in OwnCloud.
For documents, if you are even slightly techie, hosting your own OwnCloud/NextCloud is pretty easy. It just works. Both also offer a central calendar function, if that is important.
For email, buy your own domain, and host it with a local provider.
All the other things he mentions (to-do lists, password manager, etc.) just pick your favorite app, and store the data in OwnCloud.