I have a Garmin InReach and it can send location periodically. While it is more effective to have it out and pointed at a satellite, it still works in my pocket, but may just take a little longer to send the messages. For a feature like Find My, many people won’t mind if the location being sent is a little stale, but with emergency SOS, you really want your message to go out ASAP, so it makes sense that you need to point at a satellite for SOS, but not for Find My tracking.
The InReach Mini has a helix antenna specifically built for maximum gain towards the sats though. The iPhone doesn't. Apple has even built in a pointing feature for it.
You can't even realistically point the InReach Mini at a satellite because it doesn't tell you where they are. At any time there's only a couple of iridium sats in view and they move quite fast across the sky.
But the device has an antenna with the right amount of upwards gain and the right polarisation to deal with that. For an iphone it's a lot harder to incorporate that.
