Re: "it looks like it's safest to only run Zoom while on active calls"
soft toggle buttons.
on a recent (mine is 5+ years) iPhone, turning off wifi effectively just disconnects from the current wifi net for 24hrs, it'll still connect to other wifi nets and self activate after 24hrs.
same story with bluetooth.
there where some stories I think from Snowden that microphones etc would still activate when handsets where off, many derided those stories but we now know these devices don't actually do what they we expect or they are telling us they are doing.
treat turning things to off as the os telling you its off but it in fact it's still on.