One thing you have to remember is that you aren't just running Android 8, 9, 10, you are running
LG's software based on Android 8, 9, 10, which will include extra features LG have added and may not include Android features that LG decided not to include (replace "LG" with any other manufacturer and the same is true). Hence when an "Android 9 upgrade" removes a feature you don't necessarily know whether that is because Android 9 does not include it or because LG decided to change/move/remove it.
I can tell you that double tap to wake didn't change at all between Android 8, 9, 10 and 11 on the Pixels. Android version made no difference at all to my keyboards either, so I suspect that any changes there will be because you are using an LG keyboard (word correction is always a feature of the keyboard app, and never a part of the operating system). Like
@The_Chief I can't comment on the gallery memo feature because I never even knew it existed (and wouldn't have used it anyway), so don't even know whether that's an Android feature or an LG Gallery feature.