it’s the same for me to ..
I’ve been suffering from this issue for like a month my IPhone is Xs and Since I updated the iOS to 14.0 the cellular signal disappeared now and then and won’t come back until I shut the phone down and I updated the iOS to 14.2 to and still didn’t fixed ..
and when I tried to get their help they give the same list you wrote and none of them work so the only thing I have left is as they told me to restore and recovery my iPhone