I don’t really trust it. The sports bands (which I find most comfortable) are especially vulnerable to being “scooped” off the wrist with two fingers in a single motion without interrupting the presence detection.

Somehow I doubt this is true.

My Apple Watch 7 regularily "forgets" that I am still wearing it. I have to enter my code roughly 2 times a day.

So to me, it feels like presence detection actually fires way to often in situations where the watch is still on the wrist.

Do you have any more info on that? I've been able to find videos of people taking the sports band off, but it didn't look like any of the techniques were attempting to avoid interrupting the wrist presence detection

You can try this on yourself pretty easily.

Two fingers under the watch (far enough to cover the heartbeat sensor) and a swift upwards yank will pop the strap underneath and it’ll lift right off.

The thing is, if someone has your unlocked watch, what can they really do? This is a question I’ve never really known the answer to and doubt you ever would know clearly.

Certainly banking apps don’t seem to have a lot of functionality on watchOS, but I’m unsure to what extent being signed in on an unlocked watch is the same as being signed in on an unlocked phone. Can i authorise a new phone just from the watch? I can certainly get 2FA codes to the watch, so the answer I guess is maybe.

Well I'll be damned, so you can. With a watch alone they'd have limited access, but if you steal somebody's watch without the watch realising it's been removed & also steal their phone you can almost certainly unlock the phone with the watch (my partner + I use that all the time when driving... they pick up my phone, show it only their eyes, and the phone assumes it must be me wearing a mask and so it uses my unlocked watch on my wrist to unlock the phone).

The good news, however, is that you don't appear to be able to use the Apple Watch mask unlock feature to pass further Face ID checks deeper in the system once unlocked, so your banking apps & password manager is safe... but your messages & e-mails are not...

Wow this is wild, didn’t even consider this scenario and my band easily fits 2 fingers underneath to pop off the watch!

It won’t unlock the MacBook if the watch is taken off your wrist though, the watch will lock.

They said without triggering the presence detection, so presumably the watch would not lock in that case.

For sure!

Now that I have an apple silicon Mac and a keyboard with touch id, I turned that feature off.