Action Based Entry Schedule - Excluding User Based on SKUs

Hi there, I'm fairly new to Braze so I may have overlooked a key feature which enables me to do what I want to fairly easily. What I want to achieve is:

- If a customer purchases a specific SKU they should be added to the canvas - to achieve this I've used the action based option 'makes a specific purchase' referencing the exact SKU I'm looking at
- But I want to only target contacts who have this particular SKU and absolutely nothing else, so they would only have item purchased

Not the part I'm not sure about is excluding every other SKU, because there may be a scenario where a customer has purchased the SKU I'm looking at, but has also purchased other items with it too, so I want to avoid those contacts.

I see that there is a property filter I can use, which I think might solve the problem, but I just wanted to verify this. At the moment I've got it setup so that:

- Where 'Nested property' - [].addons[].quantity  is exactly 1 (addons is a product group we have on our website)

So theoretically this should only target customers who have a quantity of 1 of this specific SKU and absolutely nothing else purchased, is that correct? I'd appreciate any help, thanks!