I have been working on a modern typing training application for the last couple of days. One of the main motivations was to build an app with a modern UI and minimal distractions, enabling to fully focus on the training aspect. You can read more about the original idea and thought process here as well as some notes on iterating over the details here.
After adding some minimal auto close functionalities for the code training section, you can read about it here, another important feature was to make the text training part more entertaining.