Using Google Noto CJK Variable Font Collection in Android Apps

My final goal is to load fonts from a Variable Font Collection file. Most phones sold in China enable users to use custom fonts system-wide(ideally), but most of those fonts don't have full support for Unicode CJK ideographs, thus causing inconsistency, so I decided to embed Noto font into my app from the very beginning of development. I'm trying to utilize VFC to reduce the APK size.

In Compose there isn't a Font() function that takes a TTC index, so I tried defining a font family in XML file(which supports android:ttcIndex attribute), reading it as Typeface and finally turning it into a Compose FontFamily. I tried with a regular variable font at first, and when all that was done, I found that Text() didn't display text in the font weight I specified, instead falling back to FontWeight.Normal if present in font XML, or the font weight closest to that.

I put a regular variable font(Noto Sans CJK JP variable font) in /res/font directory, created a <font-name.xml> file, and the content is below:

<font-family xmlns:android="http://schemas.android.com/apk/res/android">
    <font android:font="@font/noto_sans_variable_jp"
        android:fontVariationSettings="'wght' 100"
        android:fontWeight="100"/>

    <!-- ... -->

    <font android:font="@font/noto_sans_variable_jp"
        android:fontVariationSettings="'wght' 900"
        android:fontWeight="900"/>
</font-family>

in the Activity, that XML font file is converted as Typeface:

val jp = resources.getFont(R.font.sans_jp)

and finally I set that Typeface as the fontFamily of my Text:

import androidx.compose.ui.text.font.FontFamily as ComposeFontFamily

Text(
    text = "測試文本",
    fontFamily = ComposeFontFamily(jp),
    fontWeight = FontWeight(900)
)

I expected the text to be displayed in the font weight I specified(900), but in the Preview the font weight fell back to 100(smallest weight in that file), code below:

@Preview
@Composable
private fun TypefacePreview() {
    MaterialTheme {
        Text(
            "測試文本",
            fontFamily = ComposeFontFamily(
                LocalContext.current.resources.getFont(R.font.sans_jp)
            ),
            fontWeight = FontWeight(900)
        )
    }
}

and in the app running on a physical device, the font weight 400.

By the way, when a Typeface has a fallback chain comprised of different fonts in the same font weight, there is no problem.

So [EDIT: even though I know such attempt is currently totally meaningless because that variable OTC file is ~30MB and loading it will cause OOM,] I wonder if there's something to do with how Compose treats Android Native Typeface internally.

EDIT: Some time ago I ended up implementing custom Font class and AndroidFont.TypefaceLoader object. Now the problem is that the Variable Font Collection is 30+MB for sans-serif and 50+MB for serif, causing my app to randomly crash in OOM.