Oh no, we're toast because of PPX usage

Thank you so much, everyone, for your answers! It was very helpful to discover rescript-schema as an example of an updated PPX project that uses dune directly instead of esy. I’m currently in the middle of upgrading Decco to use .ml files with Dune for the native code, and .res files for the Rescript modules. Things are going pretty well so far. We’ll see if it all works out in the end.