A list of public instances can be found at https://github.com/TeamPiped/Piped/wiki/Instances
To keep up-to date with the instances list, you are expected to dynamically parse it.
An example on how this can be done is available at https://github.com/TeamPiped/Piped/blob/85e2296dc410fd20375d623465900c55b5483da9/src/components/Preferences.vue#L202-L221
For all endpoints in this documentation, you will have to use an API url as a prefix. For example, the official instance's base URL would be https://pipedapi.kavin.rocks.
The OpenAPI specification for Piped is located at https://github.com/TeamPiped/OpenAPI/main/swagger.yaml. In order to properly view and inspect the available API routes, you
can open https://petstore.swagger.io in a web browser, paste https://raw.githubusercontent.com/TeamPiped/OpenAPI/main/swagger.yaml into the text field at the top and finally
click explore. Swagger UI allows you to test the documented API paths and see the required and returned parameters for requests and their responses.