How can I retrieve config yaml files from frontend?

Hi HA-community,

I’m writing some frontend code in order to extend some out-of-the-box HA component, but I’m stuck trying to fetch and gather some configuration from the backend side. My idea is the user could add some values in a specific and custom entry in one the typical yaml config files (I’m thinking right now in configuration.yaml, but could be another one at the same level such as automations, secrets, etc).

Which should be the better way to fetch that configurable chunk of params (JSON data)? In order to get a better understanding… Which is the purpose (and what kind of data can retrieve) methods such as hass.callWS or hass.callApi?

In order to be a bit clearer… I’d like to implement something like “panel_iframe” does, because you can write custom entries in the configuration, and that data is gathered from the frontend side and it’s rendered on the sidebar. So, how could I get a similar behaviour?

Thanks in advance!