Ravi,
Submit an incident in your tenant - start it with "PSM Request - ..." and request that they Release a specific node for extensibility.
There's typically some back-and-forth required here, as they'll want to know your business case / use case that is prompting you to submit the request. The more you can include in the initial request, typically the quicker the request can be fulfilled.
Note that sometimes the PSM requests cannot be fulfilled (for a variety of reasons) - the only way to find out is to ask, though.