So are you saying I can plug in my charger USB cable to the laptop and the other end to my computer & turn on Wi-Fi hotspot. Otherwise I don’t use that much data so I should be fine.
You said your Church has weak Wi-Fi, especially when everyone is trying to use it. Right? If your iPhone has a good cellular signal then you can configure it to be a Wi-Fi hotspot so that your iMac, laptop, iPad, etcetera can have internet access. Still, that setup would indeed use cellular data.
With that being said, if the computer can be connected to the internet via cat5 cable then that solves your dilemma because it would not use your cellular data and your iPhone would not need to be configured as a hotspot. If you cannot connect your computer to the internet via a cable then you’re stuck using the Church’s spotty Wi-Fi network or you can configure your iPhone as the Wi-Fi hotspot.
Finally, if your laptop has cellular capabilities and you have cellular service for it then enable the cellular option therein and use it, but again, you will be using cellular data.