There is one aspect people don't really talk about yet, because it is not just about "allowing sideloading". The law says "no self-preferencing". That means that installing an app from for example F-Droid has to take the exact same amount of taps with the exact same UX as installing something from Google Play. Same goes for the App Store. The point is not to allow sideloading, but to erase the word sideloading from the vocabulary of the platform and make it just like Windows in that regard.
This is not just bringing iOS to where Android is, Android is still not compliant yet either. Neither is Windows by the way, because of how they treat Edge.