They explode and cause area of effect damage. They are bombs, which can travel to and orbit a target. You can detonate them all at once with one hotkey, giving you greater instantaneous alpha damage. Any balance issues can be mitigated by adjusting cost and fitting.
One question: how many drone explosions can an exploding drone take before being destroyed?
To look at a similar example, launched bombs have resistances to their own type. A kinetic bomb for example can survive 6 other kinetic bonvs exploding, but dies at the 7th, or at the first bomb of a different damage type.
Drones too are vulnerable to area-of-effect weapons, and should be.
So how many of their own drone explosions should they be able to tank befire dying? 4, to enable a full flight of 5?
Kamikaze drones. Maybe made from the new mats found in the drone fabrication sites?
Another option is to expand the Deathless ship line and have a few different types of pods, ie: kamikaze (boom!), leech (energy), troop (boarding/capture), loot (steal cargo), etc.