The part in the flow where you select between allowing app installs for 7 days or forever is a glimpse into the future. That toggle shows the thought process that's going on at Google.

I can bet that a few versions down the line, the "Not recommended" option of allowing installs indefinitely will become so not recommended that they'll remove it outright. Then shrink the 7 day window to 3 days or less. Or only give users one allowed attempt at installing an app, after which it's another 24 hour waiting period for you. Then ask the user to verify themselves as a developer if they want to install whatever they want. Whatever helps them turn people away from alternatives and shrink the odds of someone dislodging their monopoly, they will do. Anything to drive people to Google Play only.

Do you think regular desktop computer should be locked down like this too? Scammers can also tell people to run Windows programs. Should that be banned too?

I'm fine with an opt-in lock-down feature so people can do it for their parents/grandparents/children.

Also, just let people get used to it. People will get burned, then tell their friends and they will then know not to simply follow what a stranger guides them to do over the phone. Maybe they will actually have second thoughts about what personal data they enter on their phone and when and where and who it may be sent to.

Same as with emails telling you to buy gift cards at the gas station. Should the clerk tell people to come back tomorrow if they want to buy a gift card, just in case they are being "guided" by a Nigerian prince scammer?