The EU has no leverage. Its own institutions are all 100% Microsoft shops with zero interest in changing that. The US has sanctioned staff at the International Criminal Court meaning MS suspended their Outlook accounts, and the ICC seems to have done .... exactly nothing. The chief prosecutor there had to open up a new personal account at Protonmail instead, although Protonmail keeps talking about leaving Switzerland due to new surveillance laws also so it's unclear how long it'll remain European (and of course Switzerland isn't in the EU anyway).
Simply put: can the EU do without US tech? No. Can the EU Commission do without extra tax revenues from US tech? Yes.
Simply put: can the EU do without US tech? No. Can the EU Commission do without extra tax revenues from US tech? Yes.