See rails or the docs.

Yarn

“error Command “webpack” not found.” can be a Node.js incompatibility, the default Raspbian version is too old for Rails 6.

bin/rails webpacker:install

https://gist.github.com/repent/5ea82b12e4491ff28efedafa8c5ea82b

rake db:drop
rake db:migrate
rake db:seed