I am not sure if this is possible directly from ckpt files. What I and my research collaborators do/did is just rewriting our old TensorFlow models in PyTorch and then importing the weights. But that’s probably the most tedious solution.
There are different tools like Microsoft’s MMdnn (https://github.com/Microsoft/MMdnn 65) that might be able to do this. I think the optimal way would be via ONNX, but I think the TensorFlow one is still not very stable (https://github.com/onnx/onnx-tensorflow 78). In the main tutorials repo, https://github.com/onnx/tutorials 86, the TensorFlow export and PyTorch import are both listed as “coming soon” though :).