I feel like videos are not enough as they only cover specific fields
Agree. What will bring you to "master level", or to a better level, as master is a controversial term, is practice. Especially with real-world projects.
Also Laravel's documentation is very complete, and I would advise you to "master" it first:
https://laravel.com/docs/9.x
Lastly, there are plenty of series here at Laracasts, that either cover building an app end-to-end, or dive-in into advanced topics on Laravel, here is a small list, but those kind of series are not limited to this list:
Some are older series, targeting older Laravel releases. But the concepts on each of them are still very useful, and Laravel docs makes it easy to follow to newer versions.
Sometimes I see people complaining about videos not going deep enough, but when I ask if they watched the whole series, video by video, with focus, they usually say that didn't.
I am not saying that is the case here, and neither that you will always need to watch a series end-to-end to learn from it.
But as you say you are uncomfortable with your Laravel skills and want to "master" them, I couldn't recommend more watching them end-to-end, avoiding getting distracted, and trying to replicate some of them, at least on this stage of your learning path.
Also all series in these topics are very good calls too:
I never see proper complex examples like reordering sub queries
From the docs: https://laravel.com/docs/9.x/eloquent#subquery-ordering
Read this whole section: https://laravel.com/docs/9.x/eloquent#advanced-subqueries
(Actually read the whole docs)
pagination with POST request(rather than GET)
I've never seen this either, and actually don't quite understand the need for it.
If you care to explain the use-case for this I would appreciate. The reason, maybe it is lacking tutorials, videos or references about it, is that maybe it is a very odd, uncommon or specific use-case.
POST methods are not meant to retrieve a collection of data. Actually this is a convention, but even the HTTP RFC does not recommend it. At the end you can do whatever you want, but I am curious on the use-case of such requirement.
reference: https://www.rfc-editor.org/rfc/rfc2616#section-9.5
like getting data from one relation while counting "unread" messages form another relation
From the docs, again: https://laravel.com/docs/9.x/eloquent-relationships#counting-related-models
Look at the third snippet. You may argue it is counting in the same relation with different criteria, but you can easily use different relations, and nothing prevents you to use an aggregate function, like ->withCount() while combining a call to ->with() to load another relation.
In this other snippet:
https://laravel.com/docs/9.x/eloquent-relationships#counting-related-models-on-morph-to-relationships
It evens eager load a polymorphic relation while counting data on the related result set.
examples of course but it would be nice to see very difficult queries to build to get a better understanding of the power of eloquent
I usually avoid advertising other people paid video courses here in Laracasts, for obvious reasons.
But as Jonathan Reinink is close friends with @JeffreyWay, and is even due to release a series about Inertia here at Laracasts, I guess Jeffrey would not mind taking about Reinink's course on Eloquent queries.
Search for "Eloquent Performance Patterns" course by Jonathan Reinink. Even that I just talked about it, I don't feel comfortable to link it here directly in respect to all the knowledge Laracasts gave me throughout the years. But this will be easily findable on a web search.
Also there are several series about Eloquent Techniques here at Laracasts
Again, some are old series, but concepts still apply. And of course a nice knowledge on SQL is always something that will leverage your understanding on how things work under the hood:
Would you know a book(or eBook)
Check out Spatie's books on Laravel.
perhaps hardcore videos that really go into the really difficult part of Laravel as well as...
Again, some are old series, but concepts still apply.
the most important, how to read properly the API documentation which I am very confused with, I am speaking about this: https://laravel.com/api/9.x/
When I need to reach Laravel source to understand better how something works under the hood, I usually reach to its Laravel source, either by browsing it on my IDE, or by browsing its source on GitHub:
https://github.com/laravel/framework/tree/9.x/src/Illuminate
Laravel code is very well-organized, and have comments where it needs them.
I see the value of the API browser, for those who prefer it, but I prefer looking into the source directly instead.
Prologue
Believe me, Laracasts is Laravel's (not so) secret weapon.
Of course finding real-world projects is not easy, and when not coding them for real, e.g. not for a client, or for a job, it is easy to get distracted or unmotivated.
But there are plenty of good real-world projects with a varying degree of difficulty available in GitHub, so you can study how them are built. Study them, fork them, deconstruct them, rebuild them.
Mastering any tool or technique, takes time and practice.
For example: all laravel.io's codebases are open-source, and aggregate.stitcher.io codebase is also open-source.
You could dive-in this codebases to see how some real-world projects are built.
Although a smaller codebase aggregate.stitcher.io was built by Brent Roose, who currently works at JetBrains as a PHPStorm evangelist, and he made a screencast on how he built it (easily findable on his main website, or on a web search).
And of course this is not a complete list by no means.
Hope this helps =)