Using the full vue.js doesn't have a build step either.
I started out developing UIs using petite-vue, unfortunately ended up rewriting it to use full Vue.js after running into too many of its limitations and issues, which given that it's abandon-ware wont ever be resolved. As such I'd strongly recommend against starting projects with PetiteVue and just use the ESM build of Vue.js which also doesn't require a build step, has the full feature-set, is actively used and maintained, etc.
Either way developing Web Apps (using Vue) without a build step using JS Modules is now my preference which I've written about in my Simple, Modern JavaScript post [1]
I started out developing UIs using petite-vue, unfortunately ended up rewriting it to use full Vue.js after running into too many of its limitations and issues, which given that it's abandon-ware wont ever be resolved. As such I'd strongly recommend against starting projects with PetiteVue and just use the ESM build of Vue.js which also doesn't require a build step, has the full feature-set, is actively used and maintained, etc.
Either way developing Web Apps (using Vue) without a build step using JS Modules is now my preference which I've written about in my Simple, Modern JavaScript post [1]
[1] https://servicestack.net/posts/javascript