This has been a huge question for us. We have been delaying any trip down partially because of the 2 and older rule. Every 2 year old is a different animal. Just look no further than potty training.
We have a 2 year old that finds it fun to wear a mask for about 5 minutes and then won’t do it anymore. Unfortunately, we will be delaying a trip to WDW until either the mask rule is gone or until she matures enough to wear it for the full day.