Software update file for linux arm in an unknown format. How can I find out what it's made of?

Question

linux

please don't drink right away.
In connection with the refusal of suppliers due to the current situation, it is necessary to get out.
There is a GPS device, the system is written in linux. The update file was supplied in the form XXX.Tiif
opens with 7-zip, but says that there is data after the end of the payload block.
If you read his notepad, then there is a FIITTIIF header. further encoded text, script and the archive itself.
As I understand it, a file was attached to the Tar archive with the condition for performing an update (to avoid downgrading)
How could one determine how this file is going to be built? than it would be possible to open it Without losing the block of useful data.

Answer 1

Maybe you don’t need to look at the file, but the firmware code, then how it unpacks it

Answer 2

Try binwalk utility

Answer 3

https://github.com/ash255/tiff_unpack start here