Now you go tell him that :-)
I have a self-hosted Nextcloud and my Nextcloud account connected via GNOME as an Online Account. It integrates seamlessly with Calendar, gives me a webdav mount for my files etc. I don’t have any issues. I have not added any Google accounts, and definitely no Microsoft accounts. I don’t use public clouds for private stuff.
I use this too. When SNMP is set up there are loads of things you can monitor with LibreNMS. Much less of a learning curve than Grafana + Prometheus, although the latter probably has some nice tweaks available that SNMP does not provide.