I’ve had my eye on something similar to the GT eGrade Current (flat bar, 250w wheel motor and small 250wh battery in the relatively normal sized down tube) for a while, but would consider more of a normal crank type motor and large battery too.
Preference is for something that has good geometry for a flat bar, or an extremely upright drop bar setup; my spine has had it with my current gravel bike which is a fairly upright drop bar. Otherwise pretty standard modern gravel attributes: throughaxles, clearance for at least 42-45mm tires and preferably 50mm+, solid construction, and hopefully compatible with suspension forks like the Fox 32 AX or Rockshox Rudy. Though I’d probably do an initial build with an ordinary solid fork.