...
Using the PE executable format is not actually necessary to accomplish
this (even for proper WoW64 support, I believe—though someone should
correct me if I'm wrong. At least it's not necessary for obvious
reasons.) ...
This is correct, out of morbid curiosity (back when I still had some free time) I wrote a prototype "Linux WoW64" wrapper and I can say that this 100% works without doing anything in PE. I say morbid curiosity because I made this tool able to simultaneously load 32-bit and 64-bit libraries in the same program and be able to create 32-bit thunks from a library's headers and that whole process is ... interesting.
...
Hope this was helpful for someone. I know Erich wrote a similar writeup,
but there were a couple of missing bits in that I wanted to clarify as well.
Heh, good memory - my "writeup" was more of a TLDR for end-users. This is _far_ more complete and covers a lot of the technical issues that get solved along the way.
Best,
Erich