[GianFabien]

I have very similar concerns to the OP.

The core of the problem is that the Big Tech solutions are funded by massive advertising revenues. People in general prefer free to paid solutions. Thus the small-tech companies are either trying to provide services on minuscule ad revenue and/or charge the vastly smaller user-base. Either way they cannot match BigTech for reach, etc.

My solution is to use Gmail for non-critical emails, iMail for important emails. Some FB Messenger for contact with distant relatives. For the rest I simply self-host. No cloud storage (portable HDs are cheap and easy to use). LibreOffice for what little office automation I need. And of course running Debian Linux.