You don't actually need a google fi compatible phone to switch, you just need it to join google fi. I was astonished when my coworker showed me his ipad pro (I think thats the name- the big one anyway) hooked up to fi a few weeks ago.

Wait seriously? Hot damn, I'm getting a CAT S61.

I think you just need an Android phone with dual-sim tech. Doesn't some of Motorola's lineup have that feature?

Dual sim as in the ability to have two sims? That's popular in India and the middle-east, so Motorolas yes probably. But that's not what's required for Fi.

IIRC Fi's requirement has to do with the ability of moving phonecalls smoothly between wifi and cellular. This capability used to be limited to a dozen or so phones. I don't know what the state of this is nowadays.

Edit: https://www.androidcentral.com/these-phones-work-project-fi -- I don't know which ones are good on that list, to be honest. I really liked the 6P, although it was a bit too large for my taste. I miss phones like the S3 :/