This is a convenience feature available on most android smartphones for years. It’s just now Samsung is bringing it to its smartphones and to just A55. Not even the S24 series has this feature.
The main benefit apart from reduced downtime is reduced chances of a failure making your device inoperable. If the update fails you simply boot the 2nd partition.
As for ground breaking changes and features. Android has become a mature and stable platform compared to before. It’s mostly smoothing the kinks and making incremental changes which benefit the UX. Don’t expect major changes like they used to in android 5, 7, 8, 10, 12.