Where should dynamic modules be installed?

[Ulrich Mueller]

We are going to include the first package with a dynamically loaded
module (emacs-libvterm) in Gentoo. The question arose where the .so file
should be installed? Since it is a system dependent binary, installing
it under /usr/share/emacs/ looks wrong. I cannot find anything about a
recommended install location in the documentation.

Would /usr/lib{,64}/emacs/site-modules/ be a reasonable place for this?

Also, wouldn't it be cleaner if Emacs had a separate variable (analog to
image-load-path, custom-theme-load-path, etc.) for loading of dynamic
modules, instead of reusing load-path?