We suspected it a little, but the S8 chip of the Apple Watch Series 8, SE 2nd gen. and Ultra effectively packs the same dual-core processor as the S6 (Apple Watch Series 6) and S7 (Series 7) chips. The identification codes marked with @Siguza indeed indicate that the identifier of the CPU (T8301) is identical to that of the two previous generations.
If the processor is the same, Apple may have changed other parts of the system-in-package (SiP) for managing the new Series 8 sensors, such as the new accelerometer and gyroscope, or the temperature sensor (there are two in the watch).
These three SiPs, S6, S7 and S8, are based on the A13 Bionic chip (inaugurated with the iPhone 11), engraved in 7 nm. The next-gen Apple Watch may be Apple’s chance to embrace 4nm etching at work with the A16, though there’s not much to complain about the S6’s performance and S7.
Comparison: what are the new features of the Series 8 compared to the Series 7?