I have a Samsung Galaxy Luna phone, running Android 6.0.1. It only has 8 GB of total internal storage space, with about 3 of those GB taken by the Android OS itself, and about 2 more taken up with stock apps I don't use/want. That leaves 3 GB for me to play around with, and as you can imagine, that doesn't allow many app installs. Most of the apps I have installed have been moved to an external MicroSD card, but there are still those apps whose developers have forbidden the option to move to SD. And on top of that, every time an app updates through Google Play, it moves it back to the internal storage, forcing me to uninstall some apps on the internal, update one app at a time, move it back to SD, then reinstall the apps I had to delete in order to perform the time-consuming process.
My ultimate goal is to free up space on my internal memory, all of which is taken by apps (anything else that I am able to put on the SD, such as files, is on the SD). Things I have tried to accomplish this:
Rooting my phone: Rooting my phone would allow me to uninstall the stock apps I don't use as well as use an app like Link2SD to move the unmovable apps to SD; this would perhaps be the simplest solution. However, the Samsung Galaxy Luna is an uncommon phone and it appears there is no way to root the phone (yet).
Adopting the MicroSD card as internal storage: Another simple solution. This would not allow me to uninstall stock apps, but hopefully enough space would be made free from internal storage by allowing another 32 GB space of "internal memory." But because this is a Samsung device, there is no option to adopt the SD card as internal storage.
Using ADB to force enable the option to adopt the SD: Another post on this site explains how to use ADB to force enable the option to adopt the SD card as internal storage on Samsung devices. But even after multiple tries, this method just simply does not work with my phone model.
These were the only methods I could find on the subject. It seems that I am out of luck with freeing up any more internal space than I have. I could try converting an app I would like to force move to an APK and editing it to enable the option to move to SD, but then I would have to repeat that process every time I want to update the app, plus I want having to hack the app to be my absolute last resort.
Is there any way to free up the internal storage on my phone, by forcing uninstall of the stock apps without rooting, by forcing adoptable storage using another means that I have not tried, and/or by forcing apps to the portable SD card using another method I have not tried? And a sub-question: is there a way to force Google Play to install updated apps straight to the SD card?