EvilCorp cloud
OP mentions technology stack but seems focused on desktop OS and popular applications.
Switching to a flavor(s) of Linux and document file formats sn't a huge issue. The real issue is the dependence of USA megacorps on where we store our data and how we access it. They've sewn this up nicely and it's going to be a major headache to untie it all.
The EU needs to fund an EU based could infrastructure. The EU needs it's own Amazon Cloud, Google Cloud or Microsoft Azure . We should have an EU workable alternative to Office 365 or Google Workspace. EU citizens should be able to use a PC, cellphone, get driving directions, watch TV streams or go on social media without relying on these megacorps.
The EU also needs to fund an EU based mobile OS. A fork of Android would be the logical start.
They'd need legislation for government funded services, banks, utility companies, supermarkets etc. to work on the mobile OS so no more online banking apps etc only working if downloaded from Google Play or Apple Store. Hopefully the EU will have rolled out its replacement for Visa and MasterCard too by then.