Module development and code questions

I have an Options element > Select type setup with custom options.  For this example, the custom options are different languages.  I would like the default value set for 'English' and am not sure what the YAML coding for default value should be for it.

The custom composite key for the Select type setup is 'autos_buying_a_car_language'.  The custom option/YAML coding is 'english: English'.

Thank you for your help!

I've included a mfa.install file along with my module (mfa). After a few iterations my module now installs without errors but my two new tables are not added to the Drupal database. I uninstalled my module and reinstalled when fixing errors. Here is the contents of mfa.install: (I should not need a hook_update_N() function)

To get Userdata outside Drupal (old Version), I used the following PHP-Script:

//define('DRUPAL_ROOT', '/var/www/html/drupal' );
define('DRUPAL_ROOT', dirname(dirname(__DIR__)));
require_once DRUPAL_ROOT . '/includes/bootstrap.inc';
drupal_bootstrap(DRUPAL_BOOTSTRAP_FULL);

global $user;
$uname = $user->name;
$uid = $user->uid;
$urole1 = $user->roles['2'];
$urole2 = $user->roles['3'];
$urole2 = strtoupper($urole2);

The part to get Userdata in Drupal 10 I found:

I want to alter the search query so that if a user searches

for this they will get the results for that too I want to use a custom code for this 
I am using this hook but its not working as expected can someone help me with this I am using search view for search 

function hook_views_query_alter(\Drupal\views\ViewExecutable $view, \Drupal\views\Plugin\views\query\QueryPluginBase $query) {
  // Check if the view is the search view.

}

I figured I would better post this question here than in the post-installation forum.

Here is the use case:

Nodes have a google Maps Place ID.
I want to display the rating and reviews for each node in a block that will be shown on a node page.

The google rating should also feed into structured metatags.

google APIs slow the site down, so I want to cache the block contents and set it to refresh after pageload at regular intervals, to get the data ready for the next visitor.

I am a very experienced Drupal 7 developer.  13 years.  I am now undergoing the unpleasant process of learning Drupal 10.  

What I am looking for is the definitive "how to" on module development.  Something that spells out what each of the files are, what all of the parameters are and how they interact.  From the very start: creating something that will appear on the Extend list, all the way to custom forms and menus and more advanced elements.

Any suggestions?