How about this solution?

Usage example one:

class ProductOne(
    val id: Int,
    val name: String,
    val manufacturer: String
) {
    override fun equals(other: Any?): Boolean = equalsHelper(other, ProductOne::name, ProductOne::manufacturer)
    override fun hashCode(): Int = hashCodeHelper(ProductOne::name, ProductOne::manufacturer)
    override fun toString(): String = toStringHelper(ProductOne::name, ProductOne::manufacturer)
}

Usage example two:

class ProductTwo(
    val id: Int,
    val name: String,
    val manufacturer: String
) {
    companion object {
        private val PROPS = arrayOf(ProductTwo::name, ProductTwo::manufacturer)
    }

    override fun equals(other: Any?): Boolean = equalsHelper(other, *PROPS)
    override fun hashCode(): Int = hashCodeHelper(*PROPS)
    override fun toString(): String = toStringHelper(*PROPS)
}

Helpers:

fun <T : Any> T.equalsHelper(other: Any?, vararg props: KProperty1<T, *>): Boolean {
    if (this === other) return true
    if (javaClass != other?.javaClass) return false

    for (prop in props) {
        @Suppress("UNCHECKED_CAST")
        if (prop.get(this) != prop.get(other as T)) return false
    }

    return true
}

fun <T : Any> T.hashCodeHelper(vararg props: KProperty1<T, *>): Int {
    return props.fold(31) { acc, prop -> acc * prop.get(this).hashCode() }
}

fun <T : Any> T.toStringHelper(vararg props: KProperty1<T, *>): String {
    return buildString {
        append(this::class.simpleName)
        append("(")
        props.joinToString() { prop ->
            "${prop.name} = ${prop.get(this@toStringHelper).toString()}"
        }
        append(")")
    }
}