Exactly! SDDL [0] provides a toolkit to do this all with no-code, but today is pretty limited. We will be expanding its feature set, but in the meantime you can also write code in C++ or Python to parse your format. And this code is compression side only, so the decompressor is agnostic to your format.
Now I cannot stop thinking about how I can fit this somewhere in my work hehe. ZStandard already blew me away when it was released, and this is just another crazy work. And being able to access this kind of state-of-the-art algo' for free and open-source is the oh so sweet cherry on top
[0] https://openzl.org/api/c/graphs/sddl/