I mean the pixel a series is great. I have a 6a and my wife has a 7a. But you’d have to compromise on the 3.5mm headphone jack and the SD card reader.
As previously mentioned the Xperia is probably the only option that meets everything except the price. Last I checked the Xperia is like $2-2.5k.
I wouldn’t recomend used that much as all phones basically have an expiry date with only having so many versions of android.
They abandoned letting you use the Signal app to send and recieve SMS. You still need to get a code via SMS to activate your Signal account. I believe this is what they are referring to.