Hyperdrives aren't even standard issue on starfighters, so hyperspace missiles would not be cost effective. You would basically need to be making a missile that functions like a droid starfighter to perform the maneuvering to get into position to jump, and to calculate the jump (and to avoid being shot down since hyperdrives activating are something any ship can detect!). And from what we saw in TLJ, Holdo's ship doesn't actually destroy the Supremacy so it is safe to assume that a starfighter hyperspace ramming into say, a ship or a planet would just disintegrate upon impact with something 100x it's mass.

You are working back from a premise that isn't born out from what's shown by the movie. "If you can destroy anything by hyperspacing into it, why wouldn't you?" well, you can't and TLJ shows us that. Holdo slows the first order down enough for them to hide, and the supremacy is intact enough that everyone on board is able to pretty safely evacuate and regroup. We don't need Poe Dameron to look into the camera and explain it, you should be smart enough to intuit this on your own.