Heres an update of what I recently found. it might come in handy for people like me that later on see this thread.
Last night I noticed some functionalities in the torchvision has been moved to torch::data namespace in the C++ API, specially the transform that I was looking for: so check torch::data::transforms:: out as well
Its still very crude, but it offers some good necessaities such as BatchTransform, Normalize, Transform, etc