[0]: https://blog.google/products/workspace/latest-google-hangout...
The latter feature has been enabled by Hangouts up until now. Now, it seems to be equally fulfilled by Messages. I'm not losing other Messages features, as I've never used them. I'll get to keep my unified calling and messaging across devices. I am relatively happy. I'd prefer no change, but it's been clear that Hangouts would go away for some time now.
There's also no iMessage on Android.
Also, Fi support for iPhones is listed as beta, and I don't think there's ever been full support for iPhones on Fi.
Finally, if Apple were to launch a Fi-like offering, I don't think anyone would expect even marginal support for Android devices. This is not to say that you couldn't get service working on Android, just that there would be literally 0 support from Apple for such a use case.