[sgerenser]

One issue is I don’t think software like PowerPoint or Keynote can output to a DeckLink or similar. A quick Google search indicates you need to use ProPresenter, which is a big change for someone who just wants to display PowerPoint slides.

[dkonofalski]

That's partially true but only if you're only looking at DeckLink devices exclusively (which are mostly for full video productions) that rely on some specific things to function. There are other cards that have software that can capture the video from any window and use it as an I/O source. Think OBS but to an I/O device instead of to a virtual camera.