I have no tutorial recommendation, but if you look here, [wiki] Building Pages in the OH3 UI: documentation draft (2/3) - #181 by RGroll, there is a link given to a self-made widget proposed by @RGroll. The YAML source code one helped me to understand how one can create own widgets based on oh-cell as a base and oh- and f7-elements.
Give it a try until a formal doc documentation is online…