To register a logic app consumption as an API in Azure API management service, we have a built in functionality to ‘Create from Azure Resource’ which directly lists all the Logic Apps which can be registered as an API.
The pre-requisite being Logic App should have a callable HTTP endpoint, that means, a request trigger.
Clicking on the option, you will be able to browse and select from all the logic apps which have a Request Trigger.
Same functionality is not available for workflows in Logic App standard yet.
However, we can manually register the Request trigger URL from workflows as a blank API in APIM service.
We will need to divide the Request URL into two parts to put into the backend and frontend.