[FYT Android Head Units] surfer63:
Creating an Allapp.pkg and flash it to your device

Use the (English) version of ApkPack.exe (english version attached) to unpack/repack an Allapp.pkg. (It also works with wine on Linux/MacOS)

(See this youtube link for a really quick & dirty (and unsharp, sorry) video about what scrolls on your screen when flashing such a mini Allapp.pkg)

(1) Quick example:

Create a folder Allapp

Copy some wanted apks or mods into the folder.

Use the ApkPack.exe to create the Allapp.pkg

Simply copy the "Allapp.pkg" and "lsec6521update" onto a clean FAT32 formatted SD-card or USB-stick.

Put the USB-stick into your unit and it will recognise the update and flash it to your unit.

Other options:

Copy the "Allapp.pkg", (optional) "updatecfg.txt", (optional) "config.txt" and "lsec6521update" onto a clean FAT32 formatted SD-card or USB-stick.

In my case having a 4G unit without using 4G and wanting to use Google Assistant for calls: Copy the Allapp.pkg, config.txt (see above), crruptoff (see above) and lsec6521update onto a clean FAT32 formatted USB-stick.

Note that when NOT using an updatecfg.txt, nothing will be wiped on your unit. Only added/replaced.

(2) Another example:

Create folder Allapp on your pc/laptop

add (2019-08-14) main server mod with extended navi_app.txt and "BT to background" hacks. (see my github repo. Be careful to choose the one for your specific firmware date)

add BW-RDS radio mod (see my github repo. Only choose version for Android 8.1 if you want full functionality)

add oandbackup (dk.jens.backup_305.apk) (Free and open source backup restore apk)

add latest MagiskManager-v7.3.2.apk

Use apkpack.exe (attached) to create a new Allapp.pkg by selecting the folder to be packaged, the name of the file being Allapp.pkg, and select button "Packed" (sloppy translation from Chinese)

Copy created "Allapp.pkg" and "lsec6521update" onto a clean FAT32 formatted USB-stick.

Insert in your unit and the flashing process will start (Note: It will mention "Setting to factory defaults" before flash reboot, but it is really not doing that)

After the (very quick) flash and normal reboot, you will have 2 new apps and 2 modded apps.

(3) Example for a FYT compatible SC9853i, like a Sinosmart or Zhan or "unnamed":

You can also create your own Allapp.pkg, also with a modded Joying apk as the apks are actually identical, but there is one big naming issue to take into account!

Even though the apks are identical having the same package name, they have different apk names. A normal install will check for the package name and replace the apk with that same package name, whatever its apk name (think of versions or build time stamps behind the the "normal" name). The flashing method simply looks at the apk name and will create an /oem/app/<apk_name>/<apk_name>.apk. In this case versions numbers of build timestamps will create again and again a new folder with the exact same apk and none will work.

As an example for the radio app:

Joying: 190043001_com.syu.radio.apk

Sinosmart: 190042001_com.syu.radio.apk

"Some" unbranded: 190101001_com.syu.radio.apk

Again: The apks are exactly the same but have a different name. If you simply flash one next to the other, both will not work anymore as both have the same internal package name being "com.syu.radio". So you have no radio at all.

So, how to create an Allapp.pkg with a modded Joying apk for your FYT compatible SC9853i unit?

Check the name of your unit's radio app (or BT, Video, Music app). (If you don't know how you can use my HWGet_info.apk and open the resulting HWget_info.zip and look inside the "oem_listing.txt")

Find the name of the modded Joying app.

Rename the modded Joying app to the name of your app. So for example for Joying-> Sinosmart radio app: rename 190043001_com.syu.radio.apk to 190042001_com.syu.radio.apk (Joying to Sinosmart)

Create a folder Allapp

Copy the modded and now renamed Joying radio apk into the folder (repeat if relevant for other mods).

Use the ApkPack.exe to create the Allapp.pkg

Simply copy the "Allapp.pkg" and "lsec6521update" onto a clean FAT32 formatted SD-card or USB-stick.

Put the USB-stick into your unit and it will recognise the update and flash it to your unit.

Also create an Allap.pkg for your original app so you can always flash back the original app if you want (or need) to.