The referenced document describing how to use Post install actions is the best way to do this. All of the effort going forward will be based on packages using the NI Package Manager. NI will not be adding additional functionality to Windows Installer options.
When creating an installer for a built LabVIEW application, it is very difficult (see here) to include an additional 3rd party installer (such as a device driver or application that your built application depends upon). What I'd like to see is a solution that treats 3rd party installers as first class citizens. I'm imagining a new "Additional 3rd Party Installers" page of the Installer build specification properties dialog.
This page might look something like the one in the screenshot below, allowing users to add a folder that contains the 3rd party installer files and define a command that is run inside that folder during the install process.
When LabVIEW builds the installer, it would suck the additional installer folders into the main installer and, after installing your app files and the additional NI installers, it would sequencially extract your additional 3rd party installers into a temp folder and then execute the command line to run. This is a pretty simple scheme that would really simplify the process for end users.
I'm sure I didn't address every issue of this use case, so please, everyone, feel free to add your own ideas. I'd love to hear your comments.