Canada

If you really need to go to the US - Don't bring any electronic devices with you through security or while transitioning through borders.

Leave your devices at home. Bring a single function camera with you if you want.

Once you get across the border ... buy a new or used phone. If you have friends or family waiting for you, ask them to get you a phone, maybe even an old phone or get them to buy a used phone that you can use during your stay (pay them to get it of course).

Set up your new phone - load your data through cloud based systems ... if you are organized enough, you can set up a cloud based password manager to handle all your other data services.

Then when you leave, reformat and reset your phone and either try to sell off the phone you just bought, give it away or just toss it.

Go through security again without a device.