Google has news on what you will need to do for still being able to sideload apps:

* enable developer options
* confirm that you are not tricked
* restart phone and re-authenticate
* wait one day
* confirm with biometrics that you know what you are doing
* decide if you only want unrestricted installs for 1 week or forever
* confirm that you accept the risks
* enjoy the few apps that still have developers motivated to develop for a user-base willing to put up with this

https://goo.gle/advance-flow

They even have a video up where they try to make this all sound nice and positive:
@grote "sideloading unregistered apps", also known as "installing" on Windows and Linux
@superblox @grote also on macos

@robot @grote Apple is stricter about installing uncertified software: https://support.apple.com/guide/mac-help/open-a-mac-app-from-an-unknown-developer-mh40616/mac

Still not as strict as Android though, which is saying a lot.

Open a Mac app from an unknown developer

If you try to open an app by an unknown developer and you see a warning dialog on your Mac, you can override your security settings to open it.

Apple Support