Pencil is a very realistic sketching program and good 2D animation tool for the cost (free).

Pencil2D is an easy, intuitive tool to make 2D hand-drawn animations. Pencil2D is open source and cross-platform. - ChatGPT-CN/pencil_2D ...

The Grease Pencil provides 2d animation tools within Blender's free and open-source full-3d pipeline.

Callipeg is a 2d animation app for the iPad which offers professional animation tools adapted to iOS ergonomics and design. Everything is designed for the Apple Pencil and hand gestures, from the ...