Compensate for microphone?
Some ideas: You could train the model using audio with randomly chosen speaker--mic system impulse responses applied. To get you started, there are microphone impulse response (IR) packs available, intended for music production purposes. Or you could perhaps generate synthetic impulse responses that cover the variability in real-world impulse responses. Or measure your own using various speaker--mic placements. The room will have an effect too; possibly you could use room IR packs, for reverbs.