Hi,
please see our previous answer here. We will also be expanding our FAQs, so thanks for asking.
From the two admin accounts, one is me and the other one is just used for creating accounts and similar interactions. We hope to get rid of it during this year but it needs changes on several components. It’s not really a priority.
On any Nextcloud instance, an administrator can see your files and all the information in the database. Not only nextcloud admins, also server admins (ie root). The only way to have files inaccessible is by using end-to-end encryption, which as stated on the link above we’re working to achieve this year. Nextcloud has no plans for database encryption AFAIK but we may be able to provide an additional service down the line, maybe based on EteSync; it’s not really planned yet as we need to investigate its feasibility and UX (normally it would mean losing the ability to access that info from the web interface).
Kind regards,
Arnau