Hi Moseli!
Hope you’re going good.
Given you already have a reactjs frontend, you probably want to maintain the separation of Backend and frontend. I think in your case, it would make sense in your case to build a Flask API, and have your reactjs app simply call your external API?
I wrote an answer back here, in Sep 2019 pointing to links. Since then, PyTorch has implemented TorchServing which could be of interest - blog here, docs here.