You can put a router in your vehicle, connect your voifo to it using station mode, then you can preview the live stream through rtsp://<ip address>/xxx.mov, also you can also download the record just enter the ip in your browser.
Base on this, you can write your own application to implement the cloud function
Its actually funny how you think this is a great idea and Viofo actually gave a like to...
Problem 1: Where are you going to power this router from? If only when the car is on/running, then how fast do you need to wait for the router to boot fully? usually a few 2-3 minutes, which I think is unacceptable. Also this would need you to reset the station mode on the Viofo camera as it stops searching for the station after 10 or so minutes which will require a reset on the station mode setting to start the search again. This means you need the camera to always be connected to the router, and brings the power issue to be a huge headache. You will need the most efficient router in the world. searching then buying it is extremely not user friendly. You will need deep technical skills in purchasing the right router with the right features AND not sip power like crazy. Also needs to be able to run on 12 volts. Your car battery can barely run the Viofo cam for more than 24 hours in parking mode.
Problem 2: You will need proficiency in multiple technologies, including writing applications on the router and client device of your choosing to make this work. Writing code that has to communicate over cellular signals is a pain, and will be rife with bugs unless you are a god programmer. Bringing back the infeasibility of this to more than 99.9999% of the entire population of people in this world AND that is a higher number of people who own one of these a139 pro cameras. Unless someone who open sources their project with extremely high quality details and low cost parts will make this more feasible but that is a big IF on someone ever doing that.
Problem 3: Extreme temperatures will kill the router/force a shutdown, that brings back the problem of needing to reset the station mode as mentioned in problem 1. In extreme heat, the camera will likely shut down, and will require you to blast AC in the vehicle to cool down the router and camera, and thus reinitiating the entire cloud system you built along with redoing the station mode. In extreme cold, there is more of a leniency but your router should be rated for outdoor usage as condensation could ultimately kill the electronics.
Problem 4: putting this router and battery required to power it in a location that is easily accessible for any problems that may occur, and not take up too much room that will reduce the amount of useful cargo space. I imagine this to be a small problem, but there are cars that are compact that offer enough space for most people and this will make it worse for them. Also, will need to route the wires/cables throughout the vehicle that can either be expensive AF or ruin an multiple weekends simply because it is likely to make a mistake with adding more complexities to the system. You are human, and some people will make mistakes that can cost them hours to multiple days depending on how much time they can spend on the project.
Problem 5: As mentioned, this is exceedingly time consuming. Your optimism on "...put a router..." and "...write your own application..." as if this can happen in a reasonable amount of time is laughable. Solving all the previously mentioned problems and implementing it will take literally months, maybe years for a fully functional cloud system that has all the features you wanted and reliably work.
I can keep going. I am displeased with comments like these that pretend that the user base are being lazy on implementing cloud features, when the best option is to quite literally not do it ourselves and just buy a product that implements cloud functions in the camera system.
You can eliminate the station mode issues if the camera had external storage solution instead of the worst "standard" known, SD Cards. It is laughable how much these companies need to push the fact that we need to use the
right SD CARD. Its literally brain dead on how bad the SD Card standard is when the implementations on readers and storage cards differ enough to cause fundamental issues in dashcam functionality. Heck UFS storage would be miles better but nope, SD Card it is for the extra bucks these manufacturers make from consumers that have almost no other options than deal with SD Card limitations.
/end rant