Ooof, no hardware schematics? Also missing datasheets? This projects seems like a very tall task to me without these fundamental missing pieces. Will Google release them soon or am I looking the the wrong place?
IIUC, the plan is to manufacture something completely new that runs Pebble OS. It seems likely that at least one chip they used in the original pebble is no longer available in large quantities.
If I remember correctly (and I could be wrong) Fitbit only ever bought the software side of Pebble (and the developers effectively), gutting the company and leaving Eric with the Hardware side of things...