Zoom and teams are low hanging fruit in terms of replacability. I use both with various customers. Internally we use teams. Occasionally somebody insists on webex or other tools. Meets isn't actually horrible now that Google seems to have stopped the internal battles to replace it every six months. But in the end it is very replaceable as well.
All of these tools cover the basics (being able to video call others, screen sharing, doing calls with multiple/many participants, chat, etc.). You can get most/all of that with free and OSS options. You might struggle a bit with larger meetings or some corporate networking situations.
UX wise, all of these tools are a bit challenged. It seems Google at least embraces the whole "it's just a browser app and that's fine" more than others that insist standalone applications are the way to go. And since these applications are effectively electron applications that run mostly fine in a browser, it is a bit of a smoke and mirrors thing in any case. Bloated is a word that is used frequently in relation to these apps.
It would be nice if tools like this could rally around federated solutions and open protocols. Actually, the smart thing for France (and other countries that care about ending the miserable status quo) would be to dictate usage of open protocols, identity, and security standards. You are welcome to connect with zoom, teams, meets and whatever as long as people not paying for those tools can still participate in a call using whatever compatible tool they prefer. Give these tools a chance to adapt and compete on features. The solution maybe isn't another app but just forcing this market out of the stone age of moats, "owning" user identities, etc.
Email is the one that got away before Silicon Valley got its act together. MS, Novel, America Online, and others completely failed to get their grubby fingers on the space before email was so widely used that not supporting full interoperability with non proprietary email servers was economical suicide. And they tried really hard. Video calls should be the same. And calendars. And word processors (a space that hasn't had any meaningful innovation in decades), spreadsheets, and all the rest. Most of MS Office is a commodity at this point. Not particularly good at anything it does actually. MS has been moving deck chairs around on the deck of that sinking ship for a few decades now.