So far, I've always used MathPad for these kind of things (not the MathPad currently in the App Store, but the one written by Mark Widholm). That's an ancient application: first version was 1993, the latest version (3.0.4) dates from 2012, but it still runs on Catalina. It doesn't have the "English-ish" features of numi, but for simple, sequential calculations, it looks very similar. Apart from that, it can read files, plot in 2D and 3D, and read files.

But I'm definitely going to take a look of the two you mentioned.