The next version of the PDK will include the puppet debugger by default in the form of a new pdk console command. You can view the RFC here for the console command.

In the meantime, you can install the puppet-debugger in your module’s Gemfile and run it via bundle exec command. This means you should edit your .sync.yml file to add Puppet Debugger gem to your module’s Gemfile.

# .sync.yml
      - gem: "puppet-debugger"
        version: "~> 0.14"

pdk update
pdk bundle install
pdk bundle exec puppet debugger