Hi Outpost 31,
Your script does not work on mobile because of the content of the "Coding" block:

This code will not work on mobile devices as it was previously stated
here.
Also, currently we do not support `let` inside "Coding" block: although it might work in browsers, it won't work on mobile. If you want to have consistent behaviour of you script across browser and mobile devices, please stick to ES5 inside "Coding" blocks. And by the way you don't need "Coding" block to define a variable and give it a string value: this can be done by standard blocks from "Variables" section.
Regarding your other questions: currently we don't have a way to link out of CoSpaces using script that would work both in browser and mobile apps, but we might introduce it in the future.