Pretty sure this has always been the case. Giving up a piece of information like a password has always been considered self-incrimination and therefore is a violation of your rights.
This is why you should get rid of face unlock, body unlock, fingerprint unlock etc. on your phone and just use a passcode. The police can compel you to unlock your phone using those other methods, because those aren't information locked in your head.
Might work. It's taking a gamble, though, and putting your phone in PIN mode is easy and can be done way in advance. I've been using a PIN unlock on my phone since I joined the protests in 2020.
Most Android phones usually allow you to require pin re-entry by clicking an open lock or a "Lockdown" button in shutdown menu. It seems for iOS it's Power + Volume Up/Down but I can't confirm this.
This is good info, but if you're putting yourself in a situation where you might get rounded up by cops (a protest, for example) you should not rely on being able to get to your phone quick enough to hit that.