According to Engadget, Nothing CEO Carl Pei has confirmed the existence of a successor to the Nothing Phone (1). Pei states that the pre-mentioned successor is "more premium" than the Phone (1). The CEO also stated that that the reason of Nothing's focus on the US is that the market is ripe for innovation, which is why the Phone (2)'s US launch is Nothing's top priority in 2023.
Nothing's reason for the Phone (1) not releasing in the US, at least according to GSMArena, is the simple fact that Nothing didn't have the resources to make the device up to snuff with US carrier standards, since there are some things that need to be included in the software and hardware in order to work with most carriers. They couldn't even build NothingOS in-house, since they only had 5 people on the mobile team at the time. They instead resorted to outsourcing the development.
Just to recap, the Nothing Phone (1) has a Snapdragon 778G Plus, a dual 50 MP camera, an OLED screen, 128 GB of storage, and 8 GB of RAM. This is the benchmark that the Nothing Phone (2) has to beat, and I think that they could, given their much improved resources compared to last year. It's probably going to run NothingOS 1.5, which, like One UI 5 and 5.1, is based on Android 13.