The high value resistor seems interesting. If you can find a copy, Bob Pease wrote quite a bit about the trials and tribulations of very high impedance circuits.
And the condenser microphones that I have were obsolete long before phantom power was invented. They were part of a tube type audio instrument system from long ago.
Not needing high voltage is one big advantage of the FM oscillator scheme. And it is probably more sensitive as well. Plus, no super high value resistors and no bad effects on high frequency response. Probably you can use a PLL IC to recover the audio and have a really good microphone.
And for the diaphram you can also use aluminum foil, cheap and available in different thicknesses. And not nearly as unhappy if you damage a piece of it. But much harder to solder to.. That can prevent a lot of pain.

 

One very interesting possible result of building such a microphone is gaining the ability to detect the low frequency sound, those below one hertz. An FM mike with a PLL detector can drive a strip chart recorder so you can see the waves far below one hertz. It might be interesting.

 

soldering aluminum is not too hard, just keep the air out. drop of oil and resin delivered by a sharp pin, then using same pin to remove oxide and bring the soldering iron with a small blob of solder. it need to be hot....
once the detail is tinned, clean it, press it against another already tinned conductor and heat again to join them.

other than that use active solder and ultrasonic soldering iron...

or try these
https://www.amazon.com/Simple-Welding-Rods-USA-Made/dp/B085GLVYYD/ref=sr_1_1_sspa?keywords=solder+aluminum&qid=1643060664&sprefix=solder+alu,aps,117&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExUlVPS0wzODc2WU9SJmVuY3J5cHRlZElkPUEwNTQxMzM3MUtUMFZMSEI0VFlGVyZlbmNyeXB0ZWRBZElkPUEwMDU5MzQ5M0tYN0FMMFhCMjJTRiZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=