@pichlo: that looks decent. Namely, you can see that the number of successful attempts to bring device to sleep is large and failed attempts is relatively low. I had issues with early XZ2 version where "fail" >> "success" (not anymore, now its OK).

Now when we know that it does go to sleep, question is for how long.

For that, check out sleep stats. If you have System Monitor, I presume that you use its fork - https://openrepos.net/content/ade/system-monitor-fork . The fork should have sleep graph, missing in the original version. Just check what's a usual % of sleep while device is not touched for some time (10-20 min) and NOT on charger. Normally, you would expect 90% sleep.