I'd love to see FF release Legion packs with weapons, equipment and spare heads and arms. While their figures are beautiful there is a definite lack of variety in them. Making conversions would be much easier if we had packs like these.

Lots of third parties out there doing this, but not exactly cheap. Though I bet an official FFG version wouldn't be too wallet friendly either 🤣

While definitely not exactly what you are looking for, the upcoming trooper upgrade packs have stuff like that. I don't think they include different heads, but the heavy weapon models also have extra arms if you want them to have the standard trooper weapon instead and use them as a different basic trooper. And all of those parts are technically swappable with existing models, with a bit of work.