There is in fact a remarkably useful set of well developed air launch rockets that help provide a nice “benchmark” for comparison with air launching satellites/etc using rockets. Anti-SATellite (ASAT) weapons are making similar engineering trade offs but aiming at a different set of capabilities, optimising for smaller sizes, being “rack ready” in the event war breaks out, and so on.

Unlike the more modern ship launched SM3 that is part of the Ageis system, the older ASM-135 https://en.wikipedia.org/wiki/ASM-135_ASAT was designed to be air launched in a supersonic zoom climb to get maximum speed and altitude from the aircraft in order to maximise its capabilities.

For an even better comparison, you can compare air launches ASAT missiles with sounding rockets, they have a greater similarity in their trajectories/launch profiles, so it’s easier to see what the air launch “gains” over the ground launch.

There's always also e.g. Orbital Pegasus.

Rockets tend to throttle down at lower altitudes so they're not accelerating through thick atmosphere though? So Delta V isnt much of a loss.

When not burning sideways, you have the issue of gravity drag. Specifically, all the force spent firing downwards is wasted on fighting gravity rather than gaining speed. The reason rockets go up is to get above the atmosphere. Without an atmosphere, you'd launch rockets sideways.