Format your Android phone SD card as internal

 I was struggling with my Infinix X671's 64GB ROM being consumed by a lot of apps, their cache and downloads with no way to move them out to the SD card. In comparison to these new Android version (mine being 12), the older ones were much flexible. My 128GB SD card was of no use as I wanted to continue using all these apps that accumulate data on the main internal memory.

The option to format the SD card as internal has been removed in this phone/ Android version. Someone said corrupt the SD card by formatting it using PC as FAT32 or something and then this option comes up. I somehow corrupted the SD card using some tool and this option did show up; however, it was grayed out, meaning I was unable to choose it. The only choice was portable. I was back to square one.

Finally, I found out that adb can help you out. Thats what I did as follows:

1) Enable developer mode. Settings --> About phone --> click build number 7 times.

2) The developer options shows up in the menu now. Click that and enable USB debugging.

3) Find and download USB driver for your phone on your PC or install Google's generic one with their Android Studio (https://developer.android.com/studio). Install the same.

4) Download and unzip the Android SDK tools (https://developer.android.com/tools/releases/platform-tools). Open a powershell in this extracted folder by clicking shift+right click.

5) Connect the USB cable from PC to phone. Set the phone to file transfer or the option other than charging.

6) Allow USB debugging option popping up on the phone. Select "always allow from this computer".

7) "adb devices" should show your device. If adb throws a path error, use .\adb devices.

8) Run .\adb shell and in the shell, run the following three commands:
sm list-disks (to check the id such as "disk:179,0" to be used the command below).
sm set-force-adoptable true
sm partition disk:179,0 private (If you want 25% internal and 75% external, use sm partition disk:179,0 mixed 75%. This latter may take time though)
sm set-force-adoptable false

9) Done, close the shell, unmount USB from PC, remove cable.

10) On the phone, open settings --> storage --> portable --> three dots next to SD card  --> move from internal or something similar. In my case it said 8.1GB will be moved and that it would take 13 minutes. Try it out, if it seems hung up in between like it did for me at 80%, reboot like I did. Retry. Done! Your SD card is now internal.

Dual apps on Android phones

MI/  Redmi are the only phones that I know which allow dual apps by default (at least on versions that I have used). Dual apps is different from Second space, which also is available by default. In the latter, a separate space is created with all required apps, meaning a separate login which is differentiated from the other by means of pin/pattern whatever you have set for security. The former clones apps in the same login, thereby consuming less space and both apps being available simultaneously.

Having switched to a non-MI/Redmi phone, I missed this feature for non-social media apps like banking for my aged parents. Infinix does have XClone that allows social-media apps to be cloned, but that isn't good enough. Yet, you can achieve the same result by using open-source apps, Shelter or Insular. Google Play store has the former, but the latest version isn't available on it and the old version didn't respond during installation. Instead, download and install F-droid and search Shelter or Insular there, download and install. I am using Insular now, whereby a work profile is created where you can install the apps that you need cloned from personal profile and then use the same in parallel. 

By the way, if at all any of your installations fail with work profile access errors or admin rights, use the phone's OS to delete the work profile and try again. My pre-F-droid failed Shelter installation had created a partial inaccessible work profile. On deleting it, the installation of Insular through F-droid and follow-on app-cloning, their installations from Google Play store and use went smooth. There may be initial teething issues but the more you play around or read around these issues, they don't seem so much of an issue, considering the open-source benefit you get.

Thanks to the developer community of F-droid, Shelter, Insular and others supporting open-source.