Spoiler alert: it didn’t work well. The world is not perfect and decision makers are greedy.
Edit: I see I am being downvoted. Is there an objective reason for moving back to Microsoft? Is there any objective reason to ditch implemented and working open source software project? As Wikipedia tells most of city computers were successfully migrated. And users were giving positive feedback.
from [1]:
In 2018, journalistic group Investigate Europe released a video documentary via German public television network ARD that claimed that the majority of city workers were satisfied with the operating system, with council members insinuating that the reversal was a personally motivated decision by lord mayor Dieter Reiter. Reiter denied that he had initiated the reversal in gratitude for Microsoft moving its German headquarters from Unterschleißheim back to Munich.
local decision makers in particular. Doesn't take that much to get some administrators in Munich to flip and to run into compatibility issues when every city does it independently.
Make it a five or ten year EU plan with some serious cash behind it, it's basically at this point an investment into security and autonomy of the continent.