[meredydd]

By far the best, easiest on-ramp for these users is a good web-based development environment. It will run on a public computer, or an unmodified Chromebook (preserving those security properties), and they are useful for everything from first-steps learning to Real Programming.

Of course I'm biased, because I make one (https://anvil.works) - but there are loads of great platforms out there. You can learn and practice basic Python with Trinket (https://trinket.io), or command the full complexity of a Linux workstation system with Cloud 9 (https://c9.io). (With Anvil, we aim somewhere in the middle - useful, deployable, earn-or-save-money-with-them apps, without the full horror of the Web. But my point is that there are many good choices available.)