The problem is scale. No one in the private sector makes or needs mortar rounds, so the DoD doesn't benefit from buying COTS components for them. Whereas you can pretty much just strap a grenade to a quadcopter with a few minor tweaks and you're in business. Which is more or less exactly what the Ukrainians have been doing with their surplus Soviet anti-tank grenades.
It doesn't matter if it's 'price effective per kg' - it can't disable a tank, and might not disable a soft target without a direct it.
The 900 series is the one that might be quite useful.
All of that said, we'll have to see how countermeasures work it may be that they develop rapidly to neutralize drones ...
... and then a rational actor like China takes the 'saturation approach' and launches 100's of them at a single battalion etc..
https://en.wikipedia.org/wiki/XM395_Precision_Guided_Mortar_...
Also, mortars and other artillery are subject to a counter-battery fire.
https://www.youtube.com/watch?v=0PcWS1marOA
The most interesting part is that it flies extremely fast so you'll never see it coming. Particularly how it bursts through a windshield before exploding.
I'm actually surprised we've got man-portable loitering munitions like the switchblade in use before the widespread adoption of guided mortar rounds. I'd have to imagine it's more cost effective (in terms of kilograms of high explosive on target per dollar) to make some GPS-guided or laser-guided mortars, and either use ground troops or a small UAV to provide targeting data.