Way before Git integration was a thing in Wildfly, we used a different approach.
We use an object model + generator approach.
We have a Java object model of all the config settings that change between stages / environments.
Then we have one Java class implementing the concrete settings for each logical system. (this could also be a database)
Then we use Apache Freemarker as template engine, and together with the object model we can generate standalone.xml files (and/or standalone.conf.bat) for each logical system.
On top there is some code to start and stop services and you can deploy your config changes in realtime to any running system
(check if cluster partners are running, stop service, deploy config change, start service, wait for successful deploy, repeat for every node in the cluster)
It was actually very little investment, like 100hours and this was all up and running. It works for 12 years now.