This project is uses JUCE and spleeterpp to make a simple application that runs spleeter in c++.
Credit for most of this work goes to https://github.com/gvne.
For MacOS instructions see gvne#1 (comment), but replace https://github.com/gvne/spleeterpp.git with https://github.com/diracdeltas/spleeterpp.git to get the 16kHz models.
In spleeterpp, you may have to run the initial cmake multiple times to get Tensorflow to download for some reason (or manually download and move Tensorflow to the correct location).