Your phone hasn't been a secure data-store across US national borders for 15+ years.

(if ever.)

Before entering authoritarian countries, you should factory reset the phone, add a minimum contact list, and have a process for restoring what you need from the cloud. No need to store phone in luggage.

Also better to leave the laptop at home, if you don't want to wipe it.

That wouldn't matter, you get your checked luggage before border control, don't you?

No.

Sure, if you get sent to secondary screening they may pick up your bag for you, but no.

Luggage pickup is after CBP. As far as I remember this is the case everywhere.

Every country I’ve ever travelled to, it’s: 1. Go through immigration, 2. Pick up your luggage, 3. Go through customs.

Not in any airport I have been to. Usually it's landing -> immigration (border control) -> baggage claim -> customs (just walk through if you have nothing to declare) -> exit.

Not really, in JFK terminal 4 at least, you get your luggage after passing through immigration.

Delete social media or wipe your phone and restore on your destination. On a laptop, you could use a decoy OS on a separate partition.

The best way to seem like you're not hiding something is to have something else to show.

Take out the sim and say the phone has no internet connection

They have WIFI.

Sure, if you want to look extra suspicious.