These animations are running in a <canvas>.
Any idea what the author used? Is everything produced with math (eg: a gear solver, etc)?
The author appears to be using his own functions written in vanilla JS. The Gears page loads a custom Canvas library base.js  plus an page-specific gears.js . iOS graphics appears to be an area of expertise  for the author.
(P.S. <canvas> is an interesting choice, I had expected <svg> before opening the page inspector. Separately, I love the creative use of TLD in the domain name.)
Would be nice to know about his process.
Here it appears he is importing the graphics from somewhere else converted to imperative drawing code: