I tried packing with --no-grafts to no avail.  Then starting "./bin/next" yields
in an infinite loop of "Polling platform port...", while there is a
".next-gtk-webkit" running in the background but it does not seem to work.

Let's think this through together: "next" is a Common Lisp executable that fires
up a subprocess, "next-gtk-webkit" on startup.

The sbcl-next package patches "source/ports/gtk-webkit.lisp" so that
"*gtk-webkit-command*" points to the next-gtk-webkit input, an different binary.

When the "next" is run from the Guix pack, it starts succesfully because it's
relocated.  But the compiled-in *gtk-webkit-command* still points to the
non-relocated next-gtk-webkit binary, which fails to start.  Am I right here?

If I am true here, then we've hit a big limitation of the Guix pack.  Can anyone
think of a way to handle this gracefully?

-- 
Pierre Neidhardt
https://ambrevar.xyz/