Which apps do you use for this? Keynote or something else?

Yes, Keynote is (was!) my go to. But it's been years since I've been presenter guy so I may end up with a vibe-presented custom solution if I did it today.

I've used and like https://github.com/nyblnet/bento, but more and more I'm just going to self-contained html because the effort in to get what I want is just so low.