The suppliers that suitable for the auto-publishing feature, are pretty much the same as the suppliers you set supplier rules for.
Well known, trusted suppliers, who will share things like category, tax amount and payment status across all their items are suitable for supplier rules, and thus for autosync.
Supermarket receipts, utility bills or train tickets tend to be very similar each time you use them, and are suitable for auto-publish.
Ideally, it's best to set supplier rules first, including default categories and other information, and work with just them for a while.
However, there are some suppliers that shouldn’t be provided for auto-publishing. Online shopping services, such as Amazon, where tax may vary depending on the origin of the order, or the category changing depending on the individual order are not suitable for this feature.
Once you're satisfied that the supplier rules are working properly, feel free to turn the auto-publish on. This will automatically export items from that supplier to your cloud accounting software, and saving you time and effort.