Hello, as you know, loading and uninstalling vehicles can be quite laborious. Therefore, is there a single package available containing all the vehicles? I would like to modify the textures of all units' vehicles, compile them into one package, and install all units' vehicles from a single package. If not, I will create a package myself and share it.

All vehicles? There's tens of thousands of modded vehicles available (and that's just on this site!). Even putting aside that, not everything will be to everyone's taste nor will it be relevant to every user (for example, other countries' emergency vehicles).

Also, most authors want to distribute their own work, so you usually wouldn't allow you to share their vehicles without permission in a combined pack.

You are right in this matter, but when I try to install a police car, the sheriff vehicles and the police vehicles become incompatible. Therefore, I think we can apply multiple liveries to a single package and use this in the Ultimate Backup file to achieve a more realistic situation in the game. After obtaining the necessary permissions from the individuals who prepare and share the textures, it can be shared, in my opinion.