If you want to check your dependency tree for the number of maintainers you're dealing with instead of the number of dependencies, this can be done with cargo t

If you want to check your dependency tree for the number of maintainers you're dealing with instead of the number of dependencies, this can be done with cargo tree + checking the Cargo.toml/crates.io ownership info for each of the found packages. I don't know if there's a command written to do that already, but I've done that with a small script in the past.