I self-hosted it for a while now. Works well. I track all devices I have and additionally hardwired a GPS in my car, connected to it. It supports a almost infinite list of GPS devices and protocols, so definitely you can find something on their list.
Very configurable, when I added a Bluetooth temperature beacon to the GPS in my car I was able to write specific computed attributes in it so that it converts raw value and saves temperature together with each check-in.
Yes. There are solutions to that though, that are cheap and work worldwide wherever there is a cellular range (e.g. Hologram, SimBase). They only lost cellular when I was at a really weird place (Faroe Islands), and only one of them. Trackers use very little data (depends on the tracker and config I guess, I use branded ones i.e. Teltonika)
Very configurable, when I added a Bluetooth temperature beacon to the GPS in my car I was able to write specific computed attributes in it so that it converts raw value and saves temperature together with each check-in.