This exactly is the challenge. If your first computer is a mobile device, you would not have that “bigger brother” available.
iOS does have Swift Playgrounds [1] and Android has the excellent Termux [2] but access to the built-in JavaScript engine would open a whole new set of possibilities.
[1]: https://www.apple.com/swift/playgrounds/
[2]: https://termux.com/
I was introduced to programming on a dinky little graphing calculator. My hope is that other “first computers” could offer similar opportunities for tinkering.
On iOS you also have Pythonista, Continuous, Shaderific, Codea, all much better than learning FX-4500p, FX-850P Basic.
Sadly on Android, most of the alternatives are quite lacking versus the iOS variants in capabilities and quality.
However, iOS more so than Android, has plenty of mature interactive code environments.