Writing a shipping plugin for pickup locations

-- HikaShop version -- : 5.1.0
-- Joomla version -- : 5.1.2
-- PHP version -- : 8.3.8
-- Browser(s) name and version -- : Firefox
-- Error-message(debug-mod must be tuned on) -- : -

I aim to create a new custom shipping plugin for Joomla 5 + HikaShop 5.1 that can do the following:

• Display a dropdown list at the shipping method section on the checkout page, containing possible pickup locations. The list of pickup locations is received via API connection, which I can implement.
• If the customer selects this shipping method, they must also select a pickup location.
• The selected pickup location must appear on the administration interface, in the web and email order confirmations as well.

I have developed many Joomla extensions, but I have not worked with HikaShop before. I would like to ask for help on the proper way to implement this, which functions need to be used for this.
If any sample code is available, that would be even better.

Thank you.

Hi. Thanks, I found the documentation, but for this case (having user input on the checkout) I wasn't able to find any.
About the marketplace: As far as I can see, these are commercial extensions. Do I need to pay more than €50 to get some code examples?