I ran EForth under the Subleq from Howe R.J at https://github.com/howerj/muxleq (the subleq one) first at QuickJS (trivial tasks, almost a 1:1 map from the C code, made in a hurry) and under... jsinterp.py from the infamous yt-dlp but using arrays instead of printing functions. But... if yt-dlp's "mini-JS" implements some captcha input functions... you can add I/O with ease and run EForth with what they call (not me) a "Not totally functional interpreter".

Not totally... until people there run the 110 rule program, Conway's Life, Subleq+EForth...