I believe you already know OpenProcessing.org/sketch/create has a switch to change the default p5js engine to the Processing.js (Pjs) 1.
For example, I’ve got this sketch “Repetitive Bézier Curve Patterns” for both p5js & Pjs engines:
The same for the sketch “3D Knot”:
At the top-right side, there’s a clickable vertical ellipsis that opens a panel w/ 3 tabs:
- Settings
- Files
- History
Within the Settings tab, there are the options Engine & Text Size.
And finally, under the Files tab, we can upload assets for the sketch via the Upload Files button.