I tried to find a method to get reviews and transmittals and didn't find it in BIM360 API or Data Management API. Is it possible to get it?
No API for Reviews and Transmittals exposed for BIM 360 at this time. There is a wish for Review API:
ALEX-37150: “API wish: expose Docs Review API”
We would be interested in knowing what kind of workflow you are trying to accomplish with API. It might help the product team to prioritize their work. If you want to catch the activities change, you may be able to find in activities log, which we are hoping to release near future. (Although we are always cautious to say this till we see it.)