Thanks for this image, and the super-clear instructions!
I got psql: error: FATAL: Peer authentication failed for user "postgres" when running d/boot_dev --init.
Although the pg_hba.conf in data/postgres/ had all the authentication methods set to “trust”, there was another one in /etc/postgresql/13/main/ which had the defaults (“peer” / “md5”).
I edited /etc/postgresql/13/main/pg_hba.conf, changed all the methods to trust, did d/shell and ran sv restart postgres to pick up the changes – and was able to continue by running d/bundle install; d/rake db:migrate RAILS_ENV=development; d/rake admin:create manually.
Leaving here in case it’s helpful for anyone else!