getUByteAt

@ExperimentalNativeApifun ByteArray.getUByteAt(index: Int): UByte(source)

import kotlin.native.ExperimentalNativeApi

fun main() {
    val data = byteArrayOf(0x00, 0x7F, (-1).toByte())
    @OptIn(ExperimentalNativeApi::class)
    val value: UByte = data.getUByteAt(2)
    println(value)   // prints 255
}