Speaking of ad-hoc communication channels that do not require shared infrastructure: I like the idea of https://github.com/divan/txqr which sends data using animated QR codes. An ultimate guarantee of physical proximity. The bandwidth is not comparable to WiFi 6, of course, but no OS support is required.

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cachius 2 days ago | parent [-]

With color it would be even faster! https://en.wikipedia.org/wiki/High_Capacity_Color_Barcode

	▲	cachius a day ago \| parent [-]
		The better example for colored QRs is https://jabcode.org/ by by Fraunhofer Institute for Secure Information Technology. It is more recent and actively maintained.