You can play with it, there is a docker container in the repo that you can use for development purposes! (with clang-p2996 branch)
Another option would be to copy some stuff over to the compiler-explorer and use a "single-header" version of the library there. I can facilitate this in case you are interested. They have reflection for EDG, GCC and Clang (I am only working with clang for now)
Thanks for the suggestion, let me take a good look at callbacks.
Another thing that I can't make work elegantly is compiling template functions from C++, since we have no clue to guess which types will be instantiated in the Python code (and they can even depend on user input, so only determined at runtime)
I've added a prebuilt image, so it should be straightforward to try it out. If you have any problems with working on that prebuilt image please open an issue or reach out to me!
The P2996 definitely provides a way to work with reflection, the syntax can be a bit weird at first, but it gets more and more familiar. They have some cool examples here (https://isocpp.org/files/papers/P2996R13.html)
This idea of using C++26 compiler just for codegen sounds interesting. Will definitely give it some thought, thanks for the suggestion (: