Comment by nine_k
21 hours ago
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.
With color it would be even faster! https://en.wikipedia.org/wiki/High_Capacity_Color_Barcode
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.