non-intelligent creatures and item attunement (by RAW)

[Zhorn]

By RAW; an entity just needs to be a creature to attune to an item unless there are additional stated requirements (class, caster, etc).
My question is to do with the one hour of focus and contact needed to achieve the attunement.
Say the party has a Headband of Intellect and wants to get one of their mounts to attune to it, BUT the mount is a combination of

1. Unintelligent (INT score of 3 or less)
2. No language
3. Not a humanoid or beast creature type (such as a monstrosity)

Looking for a RAW compliant/supported method to bring to the DM to get the mount to successfully attune to the item.

[heavyfuel]

In 5e's GAW (guidelines as written) I think it's unlikely you'll find anything

Maybe if you could get the horse interested in the headband for a whole hour in some way?

A Handle Animal check might be enough, or maybe you have to use magic (Speak with Animals or Illusions)

[Zhorn]

Looking at the Sending spell, the only requirement is the creature needs an intelligence of at least 1 to understand the meaning of the message, and they don't need a language as the spell takes care of all that, and they are able to respond in kind.
So at the very least i should be able to communicate an understanding of the process required and try and convince them of why they'd want to attempt the attunement...