There is a new pull request by concatime against master on the void-packages repository

https://github.com/concatime/void-packages firefox-wayland
https://github.com/void-linux/void-packages/pull/14420

Set `MOZ_ENABLE_WAYLAND` to launch firefox in wayland
See https://bugzilla.mozilla.org/show_bug.cgi?id=1522780 for reference.

A patch file from https://github.com/void-linux/void-packages/pull/14420.patch is attached