JSON dynamic array search

Here are 3 sample XML files. Each file has included my keyword “VGSNAG3” but in each file at a different position/index. I hope you can show me a way how to find the different positions of my keyword.
Sample1.xml (1.8 MB)
Sample2.xml (490.2 KB)
Sample3.xml (1.8 MB)

Thx in advanced
Brotfahrer