To be somewhat fair there, side loading an app should really have a giant warning, otherwise it would be really easy to trick less knowledgeable users into installing actual malware. It would be nice to have an easier way to install third party app stores, but to install an APK from a website/browser really should have a giant warning.

Worlds better than the competition that outright bans side loading other than a weird “only x number of apps” and “must reinstall every x days”.