I think the plant in your first picture is what was being promoted a couple of years ago as 'Hawaiian Portulaca' (Portulaca molokiniensis). I acquired one, but it is not exactly thriving here, although still alive.
Tarev, that is correct. However, I think it is a plant that only thrives in a very specific location and climate, and therefore it does not do so well elsewhere. I suppose that is the reason it is endangered.