There's growing evidence that the upcoming watchOS 7 will feature sleep tracking and a blood oxygen monitor. This was rumored previously, but now more sources are confirming the new features. This obviously suggests that the new Apple Watch Series 6 will support these features, but the new OS will also be rolled out to older watches. However, the reports claim that only the Watch Series 3 and newer will get the new software, meaning that support for Series 1 and 2 is ending (these two did receive watchOS v6.1 after they were skipped over for the v6.0 update). The blood oxygen feature...