Interesting. The original ADSBee 1090 - from some hints in the blog page
https://pantsforbirds.com/blog/page/2/ - seems to be an amplitude pulse demodulator like the GNS module. I don't understand what's on the m1090, is there room on it for both the original receiver circuit and the mentioned "sub 1GHz radio" chip? I can't spot that in the images. But yes in theory would need both types of circuits to receive both bands.
Here in the USA there are still many airplanes with Mode C transponders, and the GNS5892 module does not receive that, only Mode S (which - unlike in Europe - is rare here without also ADS-B out, AFAIK). The GNS5894, like the (GNS?) module used in FLARMs, does receive Mode C. But it only outputs the text data at 3Mbps making it unsuitable for direct input to the ESP32?