I took long videos of Photo Path with the Street View app installed on the Pixel 5.
The file was automatically split about every 21 minutes.
Each file size was about 3.6GB.
I imagine that the size of this auto-split is determined so that the file size does not exceed 4GB.
When shooting Photo Path, an instruction is displayed on the smartphone screen to point the camera forward, but it seems to be processed normally regardless of whether it is facing backwards or sideways.
Taken in front of the direction of travel: https://goo.gl/maps/C5skugRNNsjNLvVg6
Taken backwards: https://goo.gl/maps/wtamT571L82Zs9TG6
Taken sideways: https://goo.gl/maps/aaDA9XZPiL5X57HP9