There was the Munich public administration before that ran everything on Linux 2003-2017 until MS paid for a big new HQ in Munich - I don’t know if the then mayor, Dieter Rieter, had any direct incentives. The French Gendarmerie have been using their version of Linux too (Gendbuntu) since 2005. Regions of the PA in Spain use it too. It’s also fairly common in European militaries.