I am using the Debut theme, which I like a lot. When customising the home page there are options to add a 'Section', for example;
Unfortunately these sections can only be added to the home page from the site customisation page.
Is it feasibly possible to add these sections to custom pages (i.e. the pages you create yourself, such as About Us, etc)?
I can see in Themes > Edit Code > Sections there are sections for things like featured-blog.liquid, map.liquid, etc, so it does seem like it's possible.
Can anyone show me the code to insert on a custom page to show, for example, a section for an Image with Text Overlay?
Unfortunately sections are limited to the home page only right now. At Unite 2019, Shopify announced the new store design experience. This isn't fully available yet, but when it is, it will expand the availability of sections to pages other than the home page.
In the interim, you will need to edit the code yourself and hack up the liquid templates that you found. Because those templates use the 'section' object, which can only be created by Shopify's backend code, you will need to create a copy of each one that you wish to use and modify it remove the references to the section object, and instead to hardcode your desired values.
I am in the same boat as you - I like using the Debut theme but I am wanting to create custom contact pages with map sections. Simply embedding the map is not working correctly and the effect is being lost.
Did you succeed in selecting sections of the code from the homepage to create your custom pages?
Unfortunately I didn't solve this myself. As Code402 said above, the new store design experience should be coming soon which will enable this, so I have decided to wait instead of manually editing backend code.
All the best,