The "Project Norebo" bootstrap system that this is based on is such a text-only adaptation. It's used for building Oberon system images from a machine that isn't itself running Oberon. Norebo works by taking what is otherwise a full-fledged Oberon system, NOP-ing the hardware display routines and relevant GUI setup, and then it hooks all writes that are destined for Oberon.Log (the text object that appears in the top right viewer by default on a vanilla Oberon system). The build scripts run this system in a headless emulator, and the text written to that log gets dumped over a serial interface instead, which eventually appears in the terminal as stdout.

Here's a two minute video showing these build scripts running twice in a modified Norebo environment and producing identical disk images. The notable thing is that the first time it runs, it's actually running in a web browser―fully in a web browser, not shelling out to some cloud provider.

EDIT: Sorry about forgetting the video link. It's here: https://www.youtube.com/watch?v=TUpd70Mu0Ek