The roll-off below 200Hz is to counteract the proximity effect.
When close mic’d it has a flat frequency response.
The SM57 is intended as an instrument microphone. I’d recommend the SM58 for vocals.
MEMS and telephone microphones are generally omnidirectional, for vocals you need a unidirectional microphone, otherwise you will pick up too much background noise.

Have you tried headset microphones? Although when you are wearing it, people might mistake you for Madonna.

 

I am also interested in this project

Rather then hang on to the end of someone else's thread, it is better to start your own thread with a descriptive title that is specific to your issues. For context, you can reference this one with a link.

ak

 

The JLI microphone has its Jfet impedance converter as a follower with less gain that a toy electret mic has which produces a lower output level. But it is much larger which increases its output level to be about the same as a toy one.

BUT the Jfet follower in the JLI mic produces much less distortion at high sound levels (120dB in the datasheet) than a toy electret mic. Toy electret mics have no specs about max sound level or distortion.