This dude compare quite a lot of email providers in term of privacy. I do not necessarily agree with all its critics but it is a useful resource:
https://digdeeper.neocities.org/articles/email
I would recommend to buy your own domain in case you need to change again. That way, you’re not trapped by your email provider and you can change in case you’re not satisfied anymore
I self host a nextcloud service on my old desktop that serves as a server but every now and then the updates crash something. Sharing calendar and notes is too complicated if you don’t have a vps or a domain.
Self hosting is a pain imo. You can pay a small cloud provider with nextcloud. There is a middle ground between big tech and self hosting.
Does it mean that the swiss government will become a major open source contributor ?
Nope, sorry. Have you tried asking on the privacy space ?