It works when using 2 different RAMs regions for flash and. But I still want to understand the usage of the "dummy-flash" and if I'm setting it correctly because I'm having configuration issues #6365  (for now I submitted the PR #6366 to fix this problem).

There will be use cases where just one RAM will be available in the system for Zephyr and this RAM will have to accommodate both code and data. And to get this working I had to apply the mentioned PR and omit the "zephyr,flash" property from dts.