https://runbox.com/

Norwegian, privacy, ethical focus.

https://runbox.com/blog/2018/12/runbox-7-is-going-open-source/

Open source software powers most of the Internet, and makes up a large part of the platform Runbox is running on. Now Runbox 7 will become part of this global collaboration, and you can join in by visiting the Runbox repository on Github: https://github.com/runbox.

Not sure how much of their stack is open source but they work with providers who also specialise in open source (see ‘Partners’):

https://runbox.com/about/