As someone who is using a self-hosted vanilla Nextcloud instance and not the MurenaCloud, I can confirm, that I can
- access files on the Nextcloud (I have installed the Nextcloud app)
- auto-upload pictures taken with the camera
- sync address book, tasks and calendar (with default-installed contacts and calendar app)
- sync Notes (with default-installed notes app)
- access E-Mails on other IMAP/SMTP-servers, than those of e.foundation (with the default-installed mail app) (actually, this has nothing to do with my Nextcloud server)