If we want to get all the debug info that is set in our .vcl file to get that info we need to add extra header to request, so it should look like.

To see what will drupalSettings output you can put console log in drupalSettingsLoader.js  and this will give you info what is present in drupalSettings vars that is drupal pushing to JS 

Disabling caching on JSON API endpoints doesnt seem possible with using just below in your sevices file

Using JSON API or commerce api or even JSON API resources is great but it is limited to entities and whole architecture is aimed at them. This is fine in most cases but what if you want to output some config or some random data. You will need to get creative a bit. So what we do is then make custom drupal 8 controller, you setup the usual router yml like

I wanted to rename lots of filed and folders for my modules, but not to do it manually I made an php script that does this for me. Also I used my IDE to rename code(class names and methods). So just replace root where is the code you want to change file and folder names and do that for strings also.

You should have BREW installed and then run

brew install php@7.4

If you get problem with linking newly installed PHP and get error like

Could not symlink sbin/php-fpm
/usr/local/sbin is not writable.

next thing to do is this.
 

Not many tutorials cover this often used practices in drupal 8, so check the differences betweeen self and this
https://stackoverflow.com/questions/5197300/new-self-vs-new-static

I was wondering how PHP gets compiled to OpCodes and how does that all work, there is a nice post that talks about OpCode caching in general (a bit outdated now) and also gives a good example of how php code is tokenized for OpCode https://support.cloud.en

To force users or administrators to have predefined list of what to put into some field you will need to use one of this 2 solutions, text list or taxonomy term reference field.