I'm wondering, what are the best tools to keep an eye on system errors, failed systemd units, etc. on a desktop system (Leap 15 in my case) without manually and constantly checking log files?

On servers, I usually set up email notifications for all kinds of events, rely on logwatch to comb through my logs to look for unexpected stuff and I have a special log file that collects all messages with a priority of error and higher. Of course, I could do the same on the desktop, but I would certainly prefer a different notification path than email, namely desktop notifications would be ideal.

Just to give you an example:
Recently, I bought a new external hard drive. I set it up, put some data on it, etc. Everything looked fine from a desktop user perspective. Yet, by coincidence (I was actually trying to figure out a completely different issue), I found that the kernel was logging IO errors repeatedly, followed by a repair of the filesystem. The errors were recoverable, but I would have much preferred that I'd get a notification as a user, rather than noticing it coincidentally while combing through logs.

Are there any tools out there that can be utilized to receive desktop notifications for unusual events? Ideally, it should be customizable, so I could set up my own filters/whitelists, etc.

I'd appreciate any hints!