An alternative option is the Mozilla add-on
FEBE (Firefox Environment Backup Extension), which also works with Pale Moon. It just needs to be installed on both FF and PM. It's more for backups than for transfers, but since FF and PM are so similar, once your FF profile is backed up, you can "restore" it to Pale Moon.
At least this method has worked for me

but the migration app would probably be a lot simpler
Also consider backing up your history and passwords with
Xmarks and
Lastpass 