Rumour mill has been an NVidia SoC (derived from their automotive line) and manufactured by Samsung on a non-bleeding edge process.
https://www.eurogamer.net/digitalfoundry-2023-inside-nvidias...
The basis for the rumour is basically Linux kernel code and other leaks/hacks for a "T239" SoC that seemingly has all the streamlining and features you'd want for a mobile gaming processor (as opposed to a automotive SoC like the T234 it's supposedly derived from).
The Samsung fab is based on T234 being fabbed by Samsung using a ~5 year old process, and Korean industry rumours (https://m-mk-co-kr.translate.goog/news/business/10999380?_x_...).