Do you trust this computer

I plug my iPhone into a lot of different computers. Including a NAS. Most of the computers are just for recharging, because I have a 6s and a bad battery and I live about fifteen miles from the Apple store. It’s a geographic oddity. Whenever I plug into a Windows PC or my NAS, I get the “do you trust this computer” message. The choices are Yes or No and maybe Remember. But, of course, I don’t trust those computers (or NAS devices), I just want power. I don’t even know if I trust my iPhone for goodness sake. I suppose I should trust my NAS; there’s no danger in trusting it. I just never hit yes, because it seems like I shouldn’t. Is this device secure seems a better way of asking the question. Because do I trust Google, Facebook, Twitter, Apple, Amazon? Well, maybe Amazon. They’re at least honest with me. At least I think they are.