Actually I can not reproduce the ArchLinux issues from Cant install gintro on Arch. Using libsoup2 and libsoup3 in the same process is not supported. · Issue #190 · StefanSalewski/gintro · GitHub
libsoup3 symbols detected. Using libsoup2 and libsoup3 in the same process is not supported.
I am using Gnome as provided by recent Gentoo Linux, and just installed latest libsoup 3 from git sources. And install of the Nim bindings works fine, and I get additional the soup3.nim file.
I have to admit that I was able to reproduce the issue at the end of last year, but seems to be fixed. And indeed, we got issue reports only from ArchLinux users, like [Sugestion] remove libsoup · Issue #193 · StefanSalewski/gintro · GitHub. So I will hope that all is fine now, and will close this thread.