Personally, I would not trust anyone (e.g. ProtonMail) more than Google.

If you have sensitive things in your emails, host your own mail, use GPG encryption or a one-time pad, or even avoid electronic networked machines altogether (depending on the level of security that you require).

Switzerland-hosted services are no safer than others, recall that Crypto AG, who promised to sell secure encryption machines, were just a cover by foreign intelligence services (jointly US/DE-owned/operated by the CIA & BND).