This is and was my very first iPhone. As I decided to give it a try after over 10 years with Android. I have never had such a slow and steady failure like this before. Ever since mid July I would completely lose cellular service for 3 or more hours every week. It then happened every couple of days and the it happened every day, so I had to use my S9 Plus as a backup. No amount of updates would work, iTunes restore and DFU would come back with errors and factory resetting inside ios lead to this. Warranty expired in June and I dont have applecare. I looked up what this image meant and it came up as baseband failure, a hardware issue. I wish you guys well but I don't think I am coming back to iphone anytime soon.
Update.
I was able to get past the activation. But since this is a baseband failure. I won't be able to make calls or use data of the time.
https://preview.redd.it/semwhzl773xb1.jpeg?width=3504&format=pjpg&auto=webp&s=fab6d9647fcb0d9cbf5ce8e2b9b1d3f9e5195b75
Can you connect to WiFi?
If so, it’s not totally a lost cause, as you’d still have the ability to make calls using a 3rd-party phone app like Talkatone, TextFree (many of which can be used with Google Voice).