What is needed to enable support for embedding pypy?

Our application uses pybind11 to embed Python in a large C++ application. It's working great so far (thank you!) but we've been wondering what it would take to be able to use pypy instead of cpython.

PR #774 mentions "PyPy doesn't offer any embedding support with the CPython API"

The PyPy docs almost apologetically describe its embedding API as "very minimal and a very strange" and confirm it's different than the CPython embedding API. It goes one step further and says that that API is deprecated and that PyPy should instead be embedded using the native CFFI embedding API.

So, is pybind11 + pypy + embedding a possibility but in the "haven't gotten around to it yet" category, or is it more of a "not very feasible due to wildly different approaches" thing, or something in between, or something else? If there is just too big of a gap to overcome, I'll just move on. But if it's something that might be doable that nobody has had time to work on yet, I'd love to know if you have any thoughts to share on roughly what needs to happen - maybe it's something I could tinker with.

Thanks!

Start by reviewing PR #774 and the PyPy embedding documentation linked in the issue, including the native CFFI embedding API. Determine whether pybind11 can work with PyPy's non-CPython embedding approach and what scope support would require; the issue does not identify specific files or tests, so completion criteria are not yet defined.