The backup solution in android is indeed abysmal. adb backup -never- works for me. You can copy some, but not all, data via adb, but if you actually want to do a full nandroid backup (the only thing that's worked well for me) or use titanium backup, you need root.
Rooting with Magisk lets you hide that you have root so you can use banking apps. I think you can also just flash twrp with sp_flashtool without rooting and do a nandroid backup that way.
Best of luck!
Thanks for your reply 'amsomniac' and confirmation that it is not just me that finds Android and its means to backup data extremely poor....
Update 7th June: I have just seen a 'backup & reset' screen shot from an Android phone and it is different to the Gemini. It has a 'Back up now' button for a start, and then it shows all the active backups and individually lists the last backs up done for each of them! Why does the Gemini not have this? Is the Gemini version of Android 7 faulty in this respect? This is such an important thing, it should be the first fault to be rectified and immediately.
I find it slightly disturbing after all this time that no one else has commented about backing up, or not being able to backup AND restore with their Gemini and Android. It seems hardly anyone bothers to backup using these Android 'smart' phones if my family members are anything to go by! I've asked each of them how they back up and how often and the answers seems to be no one does!! I've also asked a couple of friends and they both lost all their data when a previous phone failed and they could not get at the old information, to install it on their new phone, so it is not just the Gemini here.
I emailed Planet support about this problem with backing up and their answer is even more worrying. I quote:
'We know for a fact that the device will take backups with Google when they're enabled. However, there is currently no option to restore those backups due to the Google setup process being replaced with our keyboard configuration software. As a lot of users had issues with configuring their keyboard due to Google's process not being designed for physical layouts, hence the change we've applied. We're looking at merging both the Google and our own setup in a future update which will allow users to restore google backups. Currently, you wouldn't be able to recover a Google backup.'
They do say that of course you can download again any Apps you had from the Google play store, even ones you've paid for, without being charged again; but that is not much comfort if you lose all the App data you have built up over a period.
Until this ability to be able to back up AND restore my data to the Gemini, I'm afraid it is not a great deal of use as far as I'm concerned and I've now switched back to my trusty Psion 3mx. I love the Gemini physically as in that respect it is really a modern Psion, but without proper integrated software and the ability to backup and restore any data, it is worthless as a PDA or mini computer which is what I really hoped for. The mobile phone use was just incidental.
I can now see why the iPhone is so much better than any Android smart phone even if their hardware is better or more advanced, because the ease of backing up or restoring is so important, and the Apple software makes that so simple and straight forward. I've used Mac desktops and laptops for years and whilst there are things I don't like about them or their total controlling element, at least they integrate superbly and if you use an iPhone, then backups are assured. I hate touch screen devices and wanted a proper keyboard and the Gemini gave me that and seemed perfect... until I really found out that the software was so lacking.
Maybe I'll have to try running it with a Linux OS full time. Does anyone know if that is really an option, especially for someone who knows almost nothing about Linux or how to set up a full time Linux OS computer?