The OpenBLAS version of NumPy (from pip rather than conda), plus PyQt5, can fit in around 100 megabytes uncompressed on disk for a Win64 binary. However I no longer recommend writing number crunching apps in Python, since you don't have thread-based parallelism due to the GIL, and have to awkwardly shuffle data across processes. (Last time I tried multiprocessing, some data can only be sent to workers on Linux using fork-based worker spawning, and not on Windows which lacks fork and requires pickling.)