They aren’t even allowing sideloading. They are allowing alternative app stores that they approve
Meh. It's basically the same thing - an alternative app store is the most user friendly way to do this anyway and the EU courts will force Apple to approve any reasonable app store.
and Apple expects a 27% cut from all app sales after it hits a million downloads.
No you're thinking of the changes Apple just made to comply with their recent loss in the USA court. That only applies to the USA.
In the EU (and only the EU) instead of charging a percentage fee there's going to be two* 50 cent fees (per user, per year). Spotify, for example, would pay $100 million per year if they choose to "sideload".
(* the app developer pays 50 cents per user per year, and whoever distributes the app also pays 50 cents per user per year)