I can't speak to security, but I bought a Mi Mix 2S some time ago and put LineageOS on it. Definitely check that the frequency bands the phone supports are util

I can't speak to security, but I bought a Mi Mix 2S some time ago and put LineageOS on it. Definitely check that the frequency bands the phone supports are utilized by your carrier. (The fastboot screen on that phone has a wee little bear wearing a People's Liberation Army hat. Take from that what you will.)