I'm already using a separate device for "official" stuff. It's a fully Google/Microsoft managed phone that runs my professional life (work profile, LinkedIn, etc.) and accesses government and some financial services. It mostly sits in a drawer outside work hours and don't use it to browse or talk to anyone outside of work. It has SimpleX installed so it can send anything I need (eg. financial statements) to my personal phone, without even needing to store my personal phone number.

My personal phone, and my personal laptop and PC, run open source OSes and are as privacy-focused as I can make thrm. They're the ones I use to browse and talk to people, both on public and private platforms. They're the ones that have my photos, my books, my passwords, my movies and my music. (I don't use streaming services, except for YouTube via Newpipe.)

I do make sure that I always have at least one bank account with a bank that doesn't require SafetyNet or similar, and can therefore be accessed without needing the "official" phone. So far, all but one of my financial service providers work fine from my personal devices.

I think the dual-device approach will quickly become the only realistic one for individuals who want privacy in their computer use (which will remain a minority). I will even say that, although Google is doing this purely for the sake of ads and profits, it is not unreasonable to expect citizens to have an "official" online presence in the form of a highly standardised Internet client, without prejudicing their ability to use other ones. In the same way that you have an official residential address, without prejudicing your ability to have other mailboxes or live on the road.