In addition to the following hidden gems in LabVIEW 2019, there are several new (non-hidden) gems in Quick Drop/palettes that are generally useful for LabVIEW development. I suggest reading the LabVIEW 2019 Upgrade Notes (once they are posted) to learn more about those VIs. But for now, here are the new LabVIEW 2019 hidden gems:
Note that for LabVIEW 2019, there is not a new Hidden Gems package on the Tools Network. Version 18.104.22.168 continues to be the latest version.