Works for me. I use the raw (AKA free ) version on X86_64 systems as well as ARM64 and even ARMHF (32 bit RpiOS, Pi Zeroes) to keep track of things on my home LAN. I even use it to report when my TP-Link smart bulbs stop communicating (ping only.) As a bonus it seems that occasional pings of the TP-Link bulbs helps to keep them in line.
Today I re-implemented a full pool backup on my laptop with encrypted rpool. In the past this resulted in errors reported in zpool status. Before the backup had even completed, checkmk had reported the errors that had cropped up. (*)
The only annoying thing is that checkmk lists every single dataset as a candidate for monitoring which can run into the hundreds on a backup server. It takes about 10s each to dismiss them. That’s annoying but something I can do while watching TV.
(*) I’ve run into this before, always triggered by the same condition. The errors are in snapshots and eventually go away when the snapshot is destroyed. I just upgraded to ZFS 2.2.3 on this host to see if that cures the problem.