Vue.js seems to be the natural choice for progressive JavaScript Apps without a build system.
We've also removed npm build systems from our newest .NET Project templates which uses JavaScript, Import Modules to progressively enhance Razor Pages Apps, which I've also written about in:
As you have access to full Vue 3 you're still highly productive being able to use Vue 3's Composition API and Plugins & Components which are able to be loaded directly in the browser.
We're still using TypeScript definitions for enabling static analysis benefits for external libraries but have switched to JSDoc type annotations for App code to avoid any runtime transpilation.
We've also removed npm build systems from our newest .NET Project templates which uses JavaScript, Import Modules to progressively enhance Razor Pages Apps, which I've also written about in:
"Simple, Modern JavaScript"
https://vue-mjs.web-templates.io/blog/javascript
As you have access to full Vue 3 you're still highly productive being able to use Vue 3's Composition API and Plugins & Components which are able to be loaded directly in the browser.
We're still using TypeScript definitions for enabling static analysis benefits for external libraries but have switched to JSDoc type annotations for App code to avoid any runtime transpilation.