What collaboration software should I use?

I’m looking to collaborate with a group of people on writing a document. Originally we used a proprietary and privacy-invasive platform, but I’m looking to try something else. Here’s some of our criteria and preferences.

  • Privacy-respecting
  • Supports real-time collaboration
  • Exports to PDF and/or Markdown (without including sensitive metadata)
  • Works on all major operating systems (both desktop and mobile)
  • Free to use
  • Preferably FOSS
  • Preferably utilizes E2EE / client-side encryption

I’ve already checked out a few options but have a few questions/concerns.

  • Cryptpad: Looks to be only available on the web. Unsure if it will work well on mobile. I’ve also used this a few years ago in the past and it was kind of buggy, though that may be different now.

  • Etherpad: From what I can tell, it’s only available on desktop. Also not sure if it must be self-hosted or if they offer free hosting.

  • Nextcloud Text: Not sure what host to pick. Also not sure if mobile is supported.

  • ONLYOFFICE: Not sure which service to use to enable real-time collaboration. Seems like Nextcloud is an option, but again I’m not sure how to pick a host.

Maybe take a look at Skiff?