Don’t waste time on this. Instead build a project, code an app, launch your startup. 6 months of that is better spent than “coding interview” preparation.
If the goal is to get a job at a FANG, then coding interview preparation is much more valuable than building a startup.
In fact, most of the work launching a startup will be on the business side anyway. Most of the coding is done in the very beginning, the rest is sales, marketing, and partnerships.