When you are using a microphone generally when not presenting the mic should point to your mouth but the hats we have point up to the ceiling and generally increases reverberation.
So if you have a 2mic hat either wall mount your Pi flat or get a 90’ degree elbow so at least your mics are pointing in a better direction and also the pcb will give an element of rear rejection.
The improvements are small but noticeable especially when it comes to the spectrograms processed in rhasspy.
To further reduce reverberation you can use this 2 mic beamformer alg but you will need something more than a Pi zero.
You have to be carefull with the 90’ adapters as they are very close to the pins being too short, but with a bit of care they are perfectly OK.
Trying to find ones with longer pins but as said fits perfect with a bit of care.