Welcome to the Atlassian developer community @IlkoMihov,
Short answer no. We talk about those APIs as open DevOps APIs; however, these are currently only available to POST events but not to GET (or query) the resulting data. The idea of APIs for consuming the data was also discussed on this thread:
At this time, I’m not aware of any public issues or roadmap items to prove that we’re considering the item. However, I will be sure your question gets to the right product manager. To that end, could you explain how you wanted to use URL or ID of a GitHub PR from the Jira REST API?