The T800's parking mode is quite a bit behind Viofo's. Additionally if you want to get by without a battery pack, of those two only the Viofo supports low power parking recording. Pretty clear cut choice.
Both cameras have their strength in different areas.
The Viofo for example has the much better parking mode. It also offers buffered parking mode and motion detection from all 3 channels. The T800 does not have buffered parking mode and only supports motion detection from the front camera.
The Viofo will use less power than the 70mai from my experience. If you don't want to use a dedicated dashcam battery then take the Viofo.
The 70mai does shine with it's polished app and cloud features. This is up to you weather you need it.
The A329S is the current king of plate capture. The T800 isn't able to reach it yet. This is also important to note.
The A329S has a cabin camera with a much wider FOV than the T800. It will capture door dings and similar much easier. However the interior camera isn't built in the main unit. This has pros and cons.
There are several review threads for both cameras on the forum. Take s look at them and make your decision depending on your requirements.
I hope this helps.