Yes. You can use as many devices as you want. You will get notifications on all logged in devices. To share notifications from the same Amazon account with a business partner, you must share your Seller Siren login info. If you create 2 different Seller Siren logins it will not work because only one account can be assigned per Amazon auth token.
Yes. It works in all available Amazon marketplaces.
Seller Siren needs to access your order data so that the app knows when to send you a sales notification. Seller Siren only accesses the minimum amount of order data needed to send your preferred notification.
Yes. You can set the app to only notify you every Xth order. So you can only get notifications every 10th, 25th, 100th, etc order.
Yes. You can filter notifications by product.
Yes. You can filter notifications by marketplace.