In the following example you can see how to add content or PHP codes before comments section in single post pages.
XTRA
How and where should I add this PHP codes?
Best solution is to add custom actions and filters in Child Theme functions.php file. But also you can create your own plugin and use this codes in your plugin.
then 'Add to home screen'
then 'Add to home screen'
Example code
Using WordPress action add content or PHP codes
In the following example you can see how to add content or PHP codes before comments section in single post pages.
How and where should I add this PHP codes?
Best solution is to add custom actions and filters in Child Theme functions.php file. But also you can create your own plugin and use this codes in your plugin.
Developer
actionbeforecommentshook