Your organisation pays Microsoft licences that increase every year, your data is hosted in the United States, and you have no leverage if pricing policies or terms of service change.

There are mature open source alternatives, deployable on-premise, that cover the essential office use cases: collaborative file management (Nextcloud), online document editing (Collabora), video communication (Jitsi, eduMEET), instant messaging (Matrix/Element), email (Postfix, SOGo).

I assess your situation, design the migration, deploy the infrastructure and train your teams. Your data stays in your datacenter, under your control.