Vladimir Sedach explains how to establish a lisp machine keyboard layout under X11. He mentions that keycaps with the right symbols have been made.

This is an Android port of EQL5 https://gitlab.com/eql/EQL5
Embedded Qt Lisp (Qt5 binding embedded in ECL, embeddable in Qt)
See also https://www.lights-of-holiness.eu/android/

A fully-free (as in libre) alternative to Github, found via
https://github.com/CodyReichert/awesome-cl