@KyleEssary I currently write outlines/manuscripts in Markdown. Runestone on iOS, almost any basic text editor on Mac (iA Writer currently).
When I speak at my home church, I use Teleprompter Premium on a back wall. I hold a small remote that lets me pause/advance when needed.
For slides, we use ProPresenter. Luckily, I’m able to use a volunteer for controlling that.
When elsewhere, I either use GoodReader or the Books app directly on an iPad. I travel with a mini because I never know the space I’ll have available on a pulpit/podium.