There is a new option in the Bake panel to enable baking to vertex colors. Unlike regular baking, this mode does not require a UV map or image to bake to, however the object must have a vertex color layer.
Thanks to:
- AutoCRC for funding
- Brech van Lommel and Dalai Felinto for their initial advice on how to implement it
- Campbell Barton for helping to make this feature work with modifiers and bmesh