How will things be broken? Google is not removing the user agent, they're just freezing it. So all sites that currently depend on the user agent will continue to do just fine. New sites can use client hints instead, which are a much more effective replacement for user agent sniffing.
This solution very specifically places the burden on "techy nerds" and not users, so I'm not sure where you're coming from.
Right, using user agent on the client side has been unsalvageably broken for a long time. Other things, like checking the existence of window.safari or window.chrome are more reliable.
For the server side, I’m not too aware of too many cases it’s useful other than analytics, and there is too much info leakage and fingerprinting happening anyway.
So killing user agent doesn’t really seem user-hostile, save for the fact that the company doing it has near monopoly market share and doesn’t need to provide a user agent, as it’s assumed that everyone is writing code to run on Google’s browser. In that sense it’s a flex.
This solution very specifically places the burden on "techy nerds" and not users, so I'm not sure where you're coming from.