The character creation rules on page 34 of the Corebook state:

"Each character may then use
the group’s starting Profit Factor to make one Acquisition (see
page 272) of a single item from Chapter V: Armoury with
an Acquisition Modifier of +0."

I realise people houserule and handwave this, but RAW - is there anything to say you can instead pick from one of the RT supplements (or one of the related games like DH)?

Since the only thing available was the Armoury at the time, I don't see an issue with at least opening it to Into the Storm.

That supplement is a ton of cut content anyways that didn't make it in to the core.

Anything else I'd rule is GM approval, but I've not seen anything official over the statement.

DH would be straight out though, they're different games and different balances.

Thanks. I figured as much.

(Only War has a black box in its supplements saying what extra equipment can be added into character creation in its supplements.)

I've looked through old threads and their seemed to be some debate over whether you could take a vehicle as your single acquisition by RAW.