somewhere in another thread here i’ve learnt this magic: nix shell --impure --expr 'with builtins.getFlake "nixpkgs"; with legacyPackages.${builtins.currentSystem}; python3.withPackages(ps: [ps.funcy])'
Just rolls off your tounge…
it doesn’t seem that there is a full feature replacement of nix-shell with new nix commands, so i’ve just added “nixpkgs” to NIX_PATH to reference the version of nixpkgs my system is built from (in flake), and deleted all channels. So this allows using “legacy” nix-shell with flake-based system