Earlier quoted context omitted.
You still make calls with your phone?
Of course, amazingly that's one of it's best features, enabling you to actually speak to a real person. (it's a type of personal connection that fleshy robots have, for some reason, derided.) But I digress, excusing your bad form of answering a question with a question, I am interested in your opinion of the possible conundrum of the two phone idea.
For a serious answer then: Rather than segregating phone calling vs the rest, if you want to go to the hassle of maintaining multiple phones, I would put sensitive apps (i.e. bank apps) separated from the rest.
But ultimately it depends on which threat model you are trying to mitigate. Most people would worry about protecting their financial information. If you are worried about possible backslash from a fascist state, you shouldn't use normal phone calls at all and switch to a privacy app.
OTOH, a dedicated phone just to make phone calls makes sense if your threat model is your significant other.