You can import and use Preact without any custom configuration needed.

To use preact/compat: (the Preact+React compatability layer) alias the “compat” package to React in your install options:

// Example: Lets you import "react" in your application, but uses preact internally
// snowpack.config.json
"installOptions": {
  "alias": {
    "react": "preact/compat",
    "react-dom": "preact/compat"
  }
}