Phones encrypt the data by default, your password or pin is also needed to authorise the connection with a computer.

However, many people do insecure things like storing passwords etc in Notes applications, or having simple PINs that are easy to guess, don’t update their devices, or even turning off security features (if they can) because they won’t take a small amount of time to understand them.

I can see two issues here:

It’s not really a storageless computer. It’s using EFI as storage to build the ramdisk.

What happens if you need to change things because of a change of cloud account, change of cloud API etc etc

Yes, that’s exactly the point. Combining data is something that must be considered. (And in some jurisdictions like the EU you even need to consider if it could be combined in future with other data)

Not sure I agree entirely. The actions I take are definitely data about me.

Also, in many jurisdictions data that could be combined (even in the future) with other data to identify you or something about you, is considered personal data.

For example, Device ID is AstridWipenaugh’s device and they use the app in the morning.

I think you’ve missed the point. It’s not the data they are collecting but the fact they say they don’t collect data.