So if we don’t want conversion, we can simply have a suitable, concise extension, and then we could in those cases:
val xs: Seq[Int] = (1).tup // Seq(1)
val ys: Seq[Int] = ().tup // Seq()
val zs: Seq[Int] = (1, 2) // Seq(1, 2)
Pretty OK, in my humble opinion. And safe. And readable.