nautilus-share and nautilus-image-converter are both old projects that ended up in the archive from inactivity. They both still function (with minor exceptions) because they are simply dialogs that call executables from maintained programs (Samba and ImageMagick).
With the release of Nautilus 43 and libnautilus-extension-4, both of these extensions fail to build because of breaking API changes and the Nautilus port to GTK4. I’ve forked the projects and ported them as necessary. My fork of nautilus-share will build against all versions of Nautilus whereas nautilus-image-converter will only build against Nautilus 43 / libnautilus-extension-4 (the archived version should be used for previous versions of Nautilus).