FWIW {fmt} already supports formatting of containers, tuples and ranges as of version 5.0 (https://github.com/fmtlib/fmt/releases/tag/5.0.0), for example:

  #include <fmt/ranges.h>

  std::vector<int> v = {1, 2, 3};
  fmt::print("{}", v); // prints {1, 2, 3}