Munich tried switching to open source (from MS Office) back in 2003.[0] It was a bit of a rough road, though I suppose no more so than many rollouts of software to enterprises. SAP implementations are a case in point. [1]

[0] https://www.zdnet.com/article/linux-not-windows-why-munich-i...

[1] https://www.linkedin.com/pulse/108-do-all-sap-implementation...

edit: typo