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

@grote 24 hours of not owning my phone is evil. This is stupid. I'm fine with everything but the pointless 24 hour wait and the biometric requirement. Give us your personally identifiable information and wait in phone purgatory for 24 hours to actually be able to own your device? Ridiculous.
@CalcProgrammer1 @grote Google is evil. It should have been clear after they change from their "don't be evil" motto.

Not sure what the thing is with PIN or biometrics. Are biometrics now required?

Anyway, if they are not evil, they should allow "sideloading enable" while doing full wipe.