My father in law was a commercial pilot and he had a home server just to keep photos and travel writing while he was flying and away from home a lot. I helped him upgrade some of that to the cloud, since that makes for sense when on the other side of the country, but he still has a bunch of stuff at home.
Antivirus as a thing is mostly dead, or has morphed into more aggressive endpoint protection. In that sense ClamAV is mostly to scan for known malware in things like mail servers. Make sure people aren’t sending malicious stuff, albeit mostly low hanging fruit.
Nextcloud, wikis, or other similar aggregation sites are also a usecase, but again low hanging fruit.
Set up a cron job and have it run periodically, like once an hour / day / week, whatever. Make sure you set up something that alerts you if/when it hits on something.