Feel free to ignore this option for now. It has no connection to the Mendix runtime environments. As we are working on expanding the functionality we will work in bringing these features together.
Longer answer (advance use-case):
For Native Mobile’s OTA we are using a service called CodePush. CodePush supports the concept of environments for updates. These environments are not connected in any way to the Mendix runtime environments.
A way to make use of this feature, currently, would be as follow:
Say you are making use of staging and production for you Mendix runtimes.
Native builder’s build command also supports the deployment-target. When used Native Builder will create an environment on CodePush using the value of the argument and associate that build with that environment.
Using the runtime-url parameter during the build, you can target the specific Mendix runtime.
This way you could have an app targetting your staging environment and one targeting production.
In the same way you can now push updates targeting environments and therefor update only the affected app.
I hope that sheds some light.
Thank you very much for your answer, Stefanos. Especially the long one!
It's very good to know that the Native builder’s build command also supports the deployment-target parameter. I was already creating different builds for different environments using the runtime-url parameter and I'll now give it at try in combination with the deployment-target. That way I can push a updated version of my app for an existing specific environment build.