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.
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.
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.