Figma Widgets are interactive objects or little tools like calculators and to-do lists that you can use with your teammates right on the canvas. Widgets were already available in FigJam, but now they've made their way to the design tool!
"Unlike plugins that run for a specific person, everyone can see and interact with the same widget. You can add as many widgets to the board as you need and even run them at the same time. This makes them great for collaboration!" (Figma widget docs)
You'll find them in a new little menu on the nav bar, or by using the Shift+I shortcut:
Here's where to find out more:
Widget Documentation (build one!)