Hrm, I’ve been using Linux as my dayjob server os of choice for about 15 years, and for my personal computer for the past 10 - and I haven’t found something like what you described. Something I would recommend is looking at a configuration management tool (Ansible is a really solid choice).
Stability issues often come from misconfiguration or just flat out configuration drift (changes over time) - something like Ansible or Chef would help with that.
Other things that touch on some of your concerns may be SELinux (wiki.debian.org/SELinux). It’s a bit of a pain to get set up, but once you do your system is much more secure. It effectively functions under the principal of least access to lock down your Debian OS, rendering the need for AV/Malware scanning somewhat moot.
I’ve done a cursory glance or two at Checkmk for monitoring, but it sounds a bit overkill for a single Debian workstation.
I mostly troubleshoot things like VPN instability or crashes by diving into /var/log or journalctl -ex to see if any googleable errors are visible.