Snipping Tool's newest Draw & Hold capability is now available to Insiders, and it's one of the best things for the tool.

Once you're on the drawing canvas, you'll see several tools at the bottom of the screen. These include a ... such as dots or lines, depending on your needs. To do this, tap the three dots at ...

Google Slides has several shapes and lines in the Insert menu ... and click New in the upper-left corner of the screen.