Torque/Power settings do not require the downgrade and can be changed in iOS/Android App, including presets. PCE interface is required for changing Region & Circumference without downgrading. If you will not include region & circumference into a preset - you can switch presets in iOS/Android App
PCE1 is not supported by Shimano anymore, only PCE02 is supported. PCE1 is supported in old 4.x versions of ETube Project for Windows.
The most cost effective solution is not to buy PCE interface, but to use a phone with Bluetooth ;)
No. Shimano released the latest FW to prohibit derestriction and changing advanced settings via Bluetooth. That was their goal.
If you don't want to downgrade - use Shimano PCE Interface with STUnlocker for Windows
Here is the list:
https://docs.google.com/spreadsheets/d/e/2PACX-1vRLxrRcdCNjNL2fGPd4QAn3KbJ7T_7O4NpYh_2lKGPWVfOgP0J5k4mB9UR4a6ZOS2mM-14fbMK40Ms0/pubhtml
The new version for Android is available. It's possible to expand dash on a full screen (hide the speedometer) by double-tap. Also it's possible to expand map/dash on a full screen at "Map" page
This message only occurs if the Android system itself interrupts the connection with the sensor and informs the app about it. There is no way to control the quality of the connection between the sensor and the Android system.