My attempts to devlop a Joomla! 4 component over Christmas for my little side project has proved hugely enjoyable as well as challenging and have given me some welcome 'rest' from the normal routine. I have however ran into a few issues.
I was using a very good bit of guidance from the joomla docs website on developing an MVC and was following this fairly well albeit with some difficulty when editing it to my needs. However, I ran into problems when the documentation 'ran out' and failed to progress beyond database usage in the Joomla 4 variant of the documentation. (I had taken a view I might as well develop a new component in Joomla! 4 from the off to save effort later). This is where I discovered my skills were just not quite good enough to take the MVC further without help from a completed documentation set, as I have databases and forms to address in the component as well as basic business processes so there is a lot going on.
I therefore took a step back (remember this is a feasibility project so I am trying to get a rudimentary site up and running and bells and whistles can follow later), and reverted to some coding on a Joomla! 3 site. Here the APIs are much better documented and I can find examples for everything I need (so far). I have bee able to easily resolve issues and do what I need so far.
So its two steps forward and one back at the moment but at leat I am making forward progress, learning new things every day, and making a workable prototype. I end the Christmas break quite happy indeed!