I built and released a Mac app I always wanted to exist:

Glassboard let's you draw over anything on your Mac, across every app and every screen, Khan-academy style!

Hold a keybind and draw. Release and it fades away. That's all! (well, except colors, shapes, a radial menu switcher and keybinds galore). But the basic concept is simple hold, draw, release, continue presenting without losing flow.

Made for frequent screensharers and content creators.

No more wiggling my mouse pointer at what I want to highlight while screensharing.

Try it at https://stem.ps/glassboard. It's completely free and will stay that.