This piece of code below will generate the arc with the circular dot based on the percentage you provide. You did get most of the part right, it was just about solving the Math Equation to find the point on the circle.

I assumed the radius of the circle as Height / 2 of the widget.

Since we are not drawing the full circle, the start angle is at 140 degrees and the maximum sweep angle is 260 degrees. (I found this by hit and trial, so that it looks as close to your image)

Now to draw the small white circle the center a.k.a offset has to be at (x,y) where x & y are given by the formula

x = radius * sin (angle in radians) y = radius * cos (angle in radians)

@Composable
fun ComposeCircularProgressBar(
    modifier: Modifier = Modifier,
    percentage: Float,
    fillColor: Color,
    backgroundColor: Color,
    strokeWidth: Dp
) {
    Canvas(
        modifier = modifier
            .size(150.dp)
            .padding(10.dp)
    ) {
        // Background Line
        drawArc(
            color = backgroundColor,
            140f,
            260f,
            false,
            style = Stroke(strokeWidth.toPx(), cap = StrokeCap.Round),
            size = Size(size.width, size.height)
        )

        drawArc(
            color = fillColor,
            140f,
             percentage * 260f,
            false,
            style = Stroke(strokeWidth.toPx(), cap = StrokeCap.Round),
            size = Size(size.width, size.height)
        )


        var angleInDegrees = (percentage * 260.0) + 50.0
        var radius = (size.height / 2)
        var x = -(radius * sin(Math.toRadians(angleInDegrees))).toFloat() + (size.width / 2)
        var y = (radius * cos(Math.toRadians(angleInDegrees))).toFloat() + (size.height / 2)

        drawCircle(
            color = Color.White,
            radius = 5f,
            center = Offset(x,  y)
        )
    }
}

Here are some examples I tried with

@Preview
@Composable
fun PreviewPorgressBar() {
    ComposeCircularProgressBar(
        percentage = 0.80f,
        fillColor = Color(android.graphics.Color.parseColor("#4DB6AC")),
        backgroundColor = Color(android.graphics.Color.parseColor("#90A4AE")),
        strokeWidth = 10.dp
    )
}

@Preview
@Composable
fun PreviewPorgressBar() {
    ComposeCircularProgressBar(
        percentage = 0.45f,
        fillColor = Color(android.graphics.Color.parseColor("#4DB6AC")),
        backgroundColor = Color(android.graphics.Color.parseColor("#90A4AE")),
        strokeWidth = 10.dp
    )
}

@Preview
@Composable
fun PreviewPorgressBar() {
    ComposeCircularProgressBar(
        percentage = 1f,
        fillColor = Color(android.graphics.Color.parseColor("#4DB6AC")),
        backgroundColor = Color(android.graphics.Color.parseColor("#90A4AE")),
        strokeWidth = 10.dp
    )
}