N800 tough. They are pretty serious about the 'tough' bit, I'm fairly sure you could use it in hand-to-hand combat and at least the phone would survive.
It has dual SIM capability but if you use that you lose the SD slot.
There is also GerdaOS (instead of KaiOS) and you can run Debian on it. When I get my next phone (which could well be years, this one is now 4 years old and still going strong) I plan on running stock linux on it to see what else you can do with it. I paid about 80 euros for it.