Me and my friend both need to access the same instance of an app at the same time. We can not just both install the app, as we both need access to the exact same instance, account, etc. We may be at different locations, yet we still want to access the app. Both of us occasionally switch off our phones, and the other one of us may need access to the app while the other person has their phone off.
We both have Android phones. We also have a cheap third Android device that we do not use.
Device 1: My device
Device 2: Friend's device
Device 3: Cheap device not currently in use.
What I am thinking about doing is installing the app on Device 3, and then leaving it at home, with the app always running, connected to WiFi and power. I guess we could then use some remote access software to access the app wherever we are.
My priorities are that accessing the app should be as simple as possible. I do not want to go login screens, authorisations, etc. every time I access it. Ideally, it should just be an icon on the home screen to click on, and preferably I should just get straight into the app. If that is not possible, then at least it should be as quick as possible with the minimum amount of steps required for access.
We do not require remote control, only remote viewing. However, remote control would also be nice.
We can use root, Xposed Framework, Magisk modules and whatever may be needed.