Google Fi doesn’t sell locked phones, so that shouldn’t be a problem.

They do have various deals that require staying on the Fi plan for some time (I’m getting the full price of a Pixel 7 back in discounts spread over 2 years), but I read that they’re delaying this increase for anyone on a promo (probably because a change of plan would allow people to exit the deal).

It’s sad for anyone who has to pay more now, but it was pretty strange that the price was actually the same for 4 lines as 2 (taxes and fees excluded).