2019 is the year of rule changes and simplifications. The Use of rangefinders (no matter whether laser rangefinders or GPS devices) is now basically allowed. However, the game management can formulate a course rule that overrides this rule. Before it was the other way around, the use of rangefinders had to be allowed by place rules.
Here you can find a short summary of all rule changes.
Training series: Golf exercise #4 - Improve your iron play
Data in golf: Angle of attack explained
Side spin explained- Data in golf