The "contract" the build pipeline has with your app is that the it will go into all of your frontend directories and run 'yarn build'. yarn build can do whatever you want/need it to do. The only requirement is that all of your resulting JS/HTML/CSS files end up in the "dist" folder at the end.

Anything that happens between yarn build and the final output is up to you. If you need a specific NPM version, we use NVM so you can specificy a specific version using a .nvmrc file in your frontend directories.