According to the official Project Fi Twitter account (@projectfi), Fi has heard customers “loud and clear” and so it will add a “Fi-compatible device at a mid-tier price” later in 2017. The handset will come from one of Google’s partners, but there’s no indication what that handset will be just yet.
As it stands right now, Project Fi supports the LG Nexus 5X, the Huawei Nexus 6P, as well as the HTC-made Pixel and Pixel XL. However, neither Nexus handset is not available to buy, so you’d have to bring your already-owned handset to sign up for Project Fi with one of those. The Pixel starts at $649 and the Pixel starts at $769, which isn’t cheap.
Adding a mid-tier price phone to Project Fi is certainly a good plan, as more options are always a good thing. It will be interesting to see which handset it is, though.