Has anyone used garden with cloud native buildpacks? Tried running the pack cli directly but getting gradle errors.

I've used Nixpacks which is similar. These are the relevant files (they're written for Acorn, not Bonsai but they should be trivial to adapt):

yaml
kind: Module
type: exec
name: nixpacks
include: ["*"]
local: true
build:
  command:
    - nixpacks build . --name lbob -o .

---
kind: Module
type: container
name: lbob
include: ["*"]
build:
  dependencies:
    - name: nixpacks
      copy:
        - source: .nixpacks
dockerfile: .nixpacks/Dockerfile
services:
  - name: lbob
tests:
  - name: unit
    args: [pytest]

---
kind: Workflow
name: my-workflow
envVars:
  SCW_VERSION: "2.10.0"
  SCW_DEFAULT_REGION: "nl-ams"
  SCW_DEFAULT_ZONE: "nl-ams-2"
  SCW_DEFAULT_ORGANIZATION_ID: "eeb9ffc1-000-0000-8c91-00000000"
  SCW_ACCESS_KEY: "SCW000000000"
  NIXPACKS_VERSION: "1.1.1"
  NIXPACKS_PYTHON_VERSION: "3.11"
  PATH: "$HOME/bin:${local.env.PATH}"
steps:
  - script: |-
      mkdir -p ${local.env.HOME}/bin
      command -v scw || curl -o ${local.env.HOME}/bin/scw -L "https://github.com/scaleway/scaleway-cli/releases/download/v${local.env.SCW_VERSION}/scaleway-cli_${local.env.SCW_VERSION}_linux_amd64"
      chmod +x ${local.env.HOME}/bin/scw 
      ${local.env.HOME}/bin/scw k8s kubeconfig install c50d7b47-1d34-40b5-b7c8-1709a6839609
      command -v nixpacks || curl -sSL https://nixpacks.com/install.sh | bash
  - command: [deploy]