I don’t know about local send specifically, but KDE Connect will do that. And if you have an FTP client on your phone, then yes you can easily spin up an FTP server on your local network and transfer files that way

Spotube is an android app that provides a frontend to Spotify and allows you to download songs you listen to to your device. Im guessing you could sync those files to your server and store them in a different system.

FreeIPA and Keycloak will give you directory management (LDAP and Kerberos), identity management, and single-sign on (OIDC and SAML) which if all your computers are running Linux as well, will give you centralized management of users.

You can then set other FOSS business management/productivity applications like NextCloud, Oodoo, Seafile, OnlyOffice, LibreOffice, CryptPad, etc. To use Keycloak as its authentication mechanism.

A lot of this will depend on what kind of work the business does.

You’ll also want to look into log management and SEIM for security monitoring, Wazuh, Graylog, and others. This is especially true if the business has any data compliancy responsibilities in the country this is in.

In that case, this seems pretty reasonable – disclaimer: I can’t personally attest to the effectiveness of this

https://github.com/Lissy93/personal-security-checklist

Inform them of their rights: https://www.ilrc.org/red-cards-tarjetas-rojas#item-4476