Thanks everyone for the useful comments and suggestions! I took most of them into account in polishing the patch for submission and more formal review (with the exception of keeping in glibc-for-fhs and the ld cache; to be discussed). I feel the patch looks much better now thanks to you all.
Please see https://issues.guix.gnu.org/56677 for the two patches to test and review. I've been using some form of the FHS container in my daily work and for testing and have found it useful, much as I wish to do these things in Guix proper. While for some this is a long way off probably (electron and JS), for others I hope this is just a useful stop-gap until software or systems are packaged for Guix. Thanks again! John
