"Cwtch is decentralized and focused on metadata-privacy in addition to communications privacy. Unlike other communication platforms, none of your messages are routed through a centralized server that has access to metadata such as your social network of friends, or who sent and received a particular message."
Looks like it's based on the onion-routed protocol used in Ricochet, so should be fairly robust (but not yet audited).
That's how they get you ;) There is a trade-off between privacy and security on one end, and convenience and ease of use on the other. Microsoft, Google and all the others profiting off of your data know this and offer you convenience and ease of use in exchange for you giving them all your data. So be prepared to give up a little of that convenience and getting a little more tech savvy.
I recommend you take a look at https://nextcloud.com/ - it's a self-hosted cloud service solution that offers file storage, calendar, notes, and a lot more. If you don't feel comfortable hosting your own just yet, there are providers out there that will host one for you for a few $ a month.