Termux. https://termux.com I've got an actual userland Linux shell and package ecosystem, with 1,231 available packages (compare against ~6k for Red Hat / CentOS, 70k for Debian), including standard shell tools, editors, and scripting languages, plus several Android-specific tools and APIs. The scripting tools open up broader archives via pip (python), npm (node.js), and cpan (perl). Many of the "Linux" shell and scr…
These days, though, there are apps and websites to do everything under the sun. If you need the power, why do the heavy lifting locally? Just use these cloud-friendly devices to connect to an SSH server via Panic’s Prompt app, or use the Shortcuts app to run Pythonista or an SSH-executed command via Siri or at a certain time (prompted). If you need something more advanced than Pythonista can support, perhaps for push notifications, you’ll probably have to use a third party app, or write your own with a Mac to set it up, but iOS is really more extensible with each new release.