This isn't a HB replacement, it's just using HB binaries. It doesn't replace HB at all. HB and this aren't full package managers when they don't officially or technically support building from source or working independently of another project's infrastructure.
A decent full package manager would support a simple, shell-like DSL like say Alpine or Arch, concurrent and parallel phases (such as downloads/builds/installs), multiple versions, reproducible builds, building from source, build acceleration, security auditing, patch management, and package cryptographic signatures (not hashes or signing of hashes).
Nix is theoretically amazing but the barrier-to-entry and gotchas for popular use make it self-limiting. Simplicity in particular areas is a price that is often paid for popularity.
A decent full package manager would support a simple, shell-like DSL like say Alpine or Arch, concurrent and parallel phases (such as downloads/builds/installs), multiple versions, reproducible builds, building from source, build acceleration, security auditing, patch management, and package cryptographic signatures (not hashes or signing of hashes).
Nix is theoretically amazing but the barrier-to-entry and gotchas for popular use make it self-limiting. Simplicity in particular areas is a price that is often paid for popularity.