Thank you both Felix and @silentmonkey. I'm navigating the M5 docs, but as I've whinged elsewhere, although they give function signatures (not complete I think, e.g. I've seen examples which don't match the reference) I'm missing context.
In relation to HTTP, there seem to be a lot of different Arduino libraries - copy and pasting from random examples on the internet has got me somewhere, but is there any guidance for a newbie as to the 'good' ones to go for? For example I'm currently able to fetch data from 'http:' URL, but not 'https:' - although the canvas.drawJpgUrl example function uses an 'https:' URL and that works...
Thanks again for responding.