Oh maybe I didn't make myself understood, but my idea with hooks also involves checking for deletion, you can check for a header in the hook to see if it's a product getting deleted, the header is supposed too look like this!
X-Shopify-Topic: products/delete
Docs: https://help.shopify.com/api/reference/webhook#events
I think this is the type of problems hooks solve very well!
This way you wouldn't have to query the /products.json endpoint every 24 hours, every action registered as webhooks will trigger the event when create/delete/update products happen, which you can mimic on ProcessWire on the handler you set on the route asignet to the webhook.
Personally I haven't tried webhooks myself, but I do have some experience using the shopify API and I believe this would be the way to go to make a one way store sync.