The latest versions of Shahed can reach 5000m in altitude, which would largely be inaudible on the ground.
If these Shahed drones have a propeller they should have a brutal signature between 0-250Hz as they are moving a lot of air.
Use one differential side and connect it to a kitchen funnel for directional listening the other one to a plastic bottle with a very very small hole in it. It will pick up everything high frequency that's different to the environmental pressure.
That way I was able to detect washing machines that had a physical link to house walls for many hundred meters (machine spinning -> house wall shaking -> pressure waves).
Add this with some GPS PPS frame timestamping and you should have a nice tracking network that doesn't require a lot of bandwidth. But maybe the setup must switch to analog differential pressure sensors as these Senirion-I2C sensors do not have a Sync ping for super precise timestamping.
Sensirion is using a thermal flow-sensing principle method which is basically a heated plate that cools/heats up when air passes it - making it extremely sensitive.
And unnecessarily so, to boot. Is the Ukrainian system open source? Can you link to it?