No shot on it being Xiaomi (or any other BBK brand like OnePlus), they haven't been super great to the custom rom community in some years now.

I would have guessed HMD, but they just pulled out of the US market: https://www.androidauthority.com/hmd-global-leaves-us-market...

However, Motorola/Lenovo seems the most logical partner, they were previously in the Android One program (which was sort of the successor to the Nexus line).

They said it'd be priced similarly to Pixels, so ~$1000 range. Afaik the only Motorola phone in that range is the Razr, but that'd be a weird choice.

I sure hope they're not excluding the a series when they say that.

Given that OnePlus is the only other vendor that currently has semi-decent custom rom support my guess is them, followed by HMD.