What is everyone doing? SELinux? AppArmor? Something else?

I currently leave my nextcloud exposed to the Internet. It runs in a VM behind an nginx reverse proxy on the VM itself, and then my OPNSense router runs nginx with WAF rules. I enforce 2fa and don't allow sign-ups.

My goal is protecting against ransomware and zerodays (as much as possible). I don't do random clicking on links in emails or anything like that, but I'm not sure how people get hit with ransomware. I keep nextcloud updated (subscribed to RSS update feed) frequently and the VM updates everyday and reboots when necessary. I'm running the latest php-fpm and that just comes from repos so it gets updated too. HTTPS on the lan with certificates maintained by my router, and LE certs for the Internet side.

Beside hiding this thing behind a VPN (which I'm not prepared to do currently), is there anything else I'm overlooking?