Sideload apps not on App Store

Sideloading history

Sideloading is last enabled in macOS 11.2. Sideloading was disabled in macOS 11.3 beta and in the current macOS 11.3 full release. If one attempts to sideload an app, the erorr message "This application cannot be installed because the developer did not intend for it to run on this platform" appears.

Sideload using appdb and Rickpactor

Visit appdb
Click 'Link your device'
Enter email address
Confirm by clicking confirmation email link
Go to System preferences, Profiles
Install the 'appdb Device Link'
Download and open Rickpactor
Enable revocation protection
Paste command into Terminal application and press return
Search on aappdb for apps

to download

Sideload with an iPhone or iPad

These methods has been disabled in macOS 11.3, these methods only work from macos 11 to 11.2.3.

iMazing

Apple Configurator 2

Download Apple Configurator 2 from App Store
Connect iPhone or iPad via USB cable
Use Apple Configurator 2 and click Add and then Apps
Sign into Apple ID
Find app to download, select and Add
A message will appear to 'Skip App', 'Replace' or 'Stop' - do nothing
Open Finder and navigate to ~/Library/Group Containers/K36BKF7T3D.group.com.apple.configurator/Library/Caches/Assets/TemporaryItems/MobileApps/ and locate the app IPA that has been download
Open Terminal and then copy and paste the command sudo xattr -rd com.apple.quarantine
Then drag the app IPA after this code (so that the path appears afterwards)
Press return
Double click on app IPA to install, which will then appear in Applications folder

Sideload without an iPhone or iPad using Windows

https://www.reddit.com/r/macgaming/comments/lc234r/running_genshin_impact_on_an_apple_silicon_m1_mac/glxdfms/?utm_source=reddit&utm_medium=web2x&context=3