nix-repl> runCommandNoCC "meow" { __structuredAttrs = true; } "meow"
«derivation /nix/store/3isnlphfrgws22950l9i2hciq1a2j8vb-meow.drv»

puckipedia@marisa ~> nix --extra-experimental-features nix-command derivation show /nix/store/3isnlphfrgws22950l9i2hciq1a2j8vb-meow.drv | jq '."/nix/store/3isnlphfrgws22950l9i2hciq1a2j8vb-meow.drv".env.__json'
"{\"buildCommand\":\"meow\",\"buildInputs\":[],\"builder\":\"/nix/store/h3bhzvz9ipglcybbcvkxvm4vg9lwvqg4-bash-5.2p26/bin/bash\",\"cmakeFlags\":[],[..],\"propagatedBuildInputs\":[],\"propagatedNativeBuildInputs\":[],\"stdenv\":\"/nix/store/lgam1kdqv5fbkwwcs7msjj9a2a5s5i4h-stdenv-linux\",\"strictDeps\":false,\"system\":\"x86_64-linux\"}"

In reply to @jade_:matrix.org
you should not be allowed to dump __json in from nixlang

In reply to @puck:puck.moe
yup. structuredAttrs is stored by just creating a big ass-__json environment variable