The Talk add-on allows returning information when the user invokes a command preceded with a forward-slash.
I have created 3 custom commands that help NextCloud admins know certain server information that would otherwise have to come from other tools ie: monitoring/graphing software:
1. Disk space used, available, and percent used via df utility
2. Latency related info via common ping utility (install if not exists for you, normally net-utils pkg or similar)
3. Listing server-side mounts via standard mount command