The question has just been discussed here.
I’m using nextcloud in gnome accounts for syncing calendar and contacts to and from a mobile running mobian. Works like on the desktop.
Mobian is mobile debian and PureOS is debian based.
There are two ways that functionality goes into PureOS:
- developed by Purism and probably upstreamed to Debian
- developed by Debian contributors and being included in PureOS with updates
If you’d really need to test your use case, you could use the qemu image.
I guess the rest of it is a bit of marketing chee-chee.