Can I use a numbered company as the buyer to keep my own name out of the deal?

You can use a numbered company as your purchasing entity, and it will keep your name off the purchase agreement itself, but it's worth being realistic about how much anonymity that actually provides. A numbered company still needs directors and officers, and depending on the transaction, your involvement can still surface through financing applications, personal guarantees, PPSA or land registrations, or simply through the seller, their lawyer, or a landlord wanting to know who's actually behind the numbered entity before agreeing to deal with it.

The nuance is that sellers, lenders, and landlords generally want comfort about who they're really dealing with, especially where a personal guarantee, ongoing lease, or vendor take-back is involved — a numbered company with no visible principal behind it can actually slow a deal down rather than smooth it over, since counterparties may simply refuse to proceed without knowing who controls it.

If genuine confidentiality matters to you, it's worth discussing with a business lawyer early what level of disclosure the deal actually requires versus what you can reasonably keep private, since a numbered company provides some administrative distance but not true anonymity.