When placing a Jukebox with a record playing next to Allay with an amethyst shard in its hands the Allay does not dance and therefore does not duplicate. I've everything tried boxing them in next to jukebox, giving them open space, using leads, taking back shards and waiting for Allay to dance, nothing works. It is currently impossible to duplicate Allay on Minecraft Nintendo Switch version.
This new feature is not available in 1.19.1.
It is currently only available in the 1.19.10.22 or later Preview/Beta.
Please see the changelogs for information on what new features are available.