Your favorite sources for: Learning API connections and plug-in type(?) builds

I am self-taught, through learning, with database background, and WordPress, website building beginner experience of 10 years depending on other tools, etc.
No funds to do to ‘paid’ courses at this time - college or otherwise - but looking for recommendations from community on places I might be able to start as if I was in kindergarten - :slight_smile:

I understand basic php, intermediate to advanced in CSS, can grasp fairly quickly/see patterns in relational databases, streamlining data entry and can step out what needs to happen

Use w3Schools to learn/test things to make sure I understand concept/get it correct
Have done Open Courses at Yale, Harvard, Princeton, in past, and retained the information

Current Core Providers/Tools:
Hosting by Flywheel, nginx server
Local by Flywheel
WordPress v 5.2.3, PHP 7.2.9, MySQL 5.7.23,
Core Themes used:
Genesis Framework
Genesis Studio Press made pro plus themes updated recently, Accessibility Ready
Cobalt Apps Dynamik child theme builder
Cobalt Apps Genesis Dev Kit

Core plugs I always/frequently use:
Classic Editor (until I do full test site in Blocks and run through Accessibility test…)
WpForms with Google reCaptcha invisible 2 (Google Platform for APIs, delays and my sometimes slow rural internet service just throw me for a loop on 'what did I do wrong…NOW?" often)

Core Values/Motivations
Support OpenSource mission, try to do whenever I can, believe in donating to free plugins if they have donation button, keep it updated and I use for client needs -

Past outside observations of my ‘self-taught’ style of doing things (while learning VBA code for Access databases - circa 2003)

“Yes, your code is long, and yes, it goes through, step by step, instead of short hand (which I had observed was used by those who had degrees in coding various things) BUT, it still runs fast, no endless loops and while it might be long, it is clean and runs fast and is notated, so let it go”

Sorry for long spiel - just thought info might help ya know what would work for me or not - if you have time to read now, saves us all time, later on! :slight_smile:

Any guidance/advice/what you love to use & recommend are greatly appreciated!!!

P.S. I write long, boring emails too - - invested in and using a mind mapping visual tool to bridge gaps in communication - maybe I should have made one for this…sigh…