I think you can start form looking at the ticket Nordic PCA10059 support without additional Seeger debugger https://github.com/zephyrproject-rtos/zephyr/issues/9055 and related PRs

As you can see what you want is actually in progress.

There is no need to modify linker script – partitions you can move using DTS overlay files – I recommend to look at zephyr developer guide for more info (and the code as well)

Andrzej