bun create astro. The create-astro package detects when you are using bunx and will automatically install dependencies using bun.
terminal
Start the dev server with
bunx.
By default, Bun will run the dev server with Node.js. To use the Bun runtime instead, use the --bun flag.
terminal
Open http://localhost:4321 with your browser to see the result. Astro will hot-reload your app as you edit your source files.

Refer to the Astro docs for complete documentation.