I watch can be used in Egypt gps+celluler

At this time, it does not appear that there is a carrier in Egypt that supports the cellular capabilities of the Apple Watch Series 3 GPS & cellular (not an iWatch). Apple Watch - Carriers - Apple

The Apple Watch contains an e-SIM that copies information from the iPhone SIM, and needs to have support from the carrier. While the Apple Watch will still work as the other Apple Watch series do, it will not at this time, be able to support cellular without the phone. There are also different versions of the Apple Watch Series 3 GPS & Cellular, so you would also need to see which version your Egyptian carrier would support. Contact your carrier to see when they may be supporting the Apple Watch. In the meantime, if you do purchase one, this will show what you can do with the Apple Watch while no having your paired iPhone. How to use your Apple Watch without your iPhone nearby - Apple Support