The always on display feature that is popular on the Samsung S7 and LG G5 came to the Samsung Z3 via the Always on Display app. This app is quite suited to the Z3 as the AMOLED screen does not use that much power to keep on compared to similar sized LCD screens.
At the time the developer Anup Kushwaha promised that more features would be Implemented over time and I'm glad to say that he has kept to his word. The latest update is to version 0.0.8 and there are a few good features that have now been Introduced.
Available to update now from the Tizen Store for the Samsung Z3.