Helper function loading annotated strings from strings.xml (might require further optimization)

annotatedStringResource.kt

import android.text.Annotation
import android.text.SpannedString
import androidx.annotation.StringRes
import androidx.compose.runtime.Composable
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.text.AnnotatedString
import androidx.compose.ui.text.SpanStyle
import androidx.core.text.getSpans

@Composable
fun annotatedStringResource(
    @StringRes id: Int,
    spanStyles: (Annotation) -> SpanStyle? = { null }
): AnnotatedString {
    val resources = LocalContext.current.resources
    val spannedString = SpannedString(resources.getText(id))
    val resultBuilder = AnnotatedString.Builder()
    resultBuilder.append(spannedString.toString())
    spannedString.getSpans<Annotation>(0, spannedString.length).forEach { annotation ->
        val spanStart = spannedString.getSpanStart(annotation)
        val spanEnd = spannedString.getSpanEnd(annotation)
        resultBuilder.addStringAnnotation(
            tag = annotation.key,
            annotation = annotation.value,
            start = spanStart,
            end = spanEnd
        )
        spanStyles(annotation)?.let { resultBuilder.addStyle(it, spanStart, spanEnd) }
    }
    return resultBuilder.toAnnotatedString()
}

Usage:

<string name="someAnnotatedString">Some <annotation url="https://google.pl">link with "url" as key</annotation</string>

spanStyle sets up optional styling based on annotation.

    val someAnnotatedString = annotatedStringResource(
        id = R.string.someAnnotatedString,
        spanStyles = { annotation ->
            when (annotation.key) {
               "url" -> SpanStyle(textDecoration = TextDecoration.Underline)
                else -> null
            }
        }
    )

And AnnotatedString.getStringAnnotations are implicitly provided to e.g. provide clickable behavior.

            ClickableText(
                text = someAnnotatedString,
                ...
                onClick = { offset ->
                    someAnnotatedString.getStringAnnotations(tag = "url", start = offset, end = offset)
                        .firstOrNull()
                        ?.let { onOpenUrl(it.item) }
                }
            )