edit an OTA update for an automotive android multimedia

Hello, i have a Multimedia system in my car that runs on Android 9,
i can use 'ADB' to enter it, but i cannot seem to be able to make changes,(there is no package installer)
i have an original OTA update for the system that i was hoping i could modify so that while updating the sytem, other apps will be added also, and to mofify the launcher also
the contents on the OTA file are [Payload.bin,/Meta inf, compability.zip]
i hope i could find a person that is good with this stuff
i could bring a lot of projects if i find a suitable person