This would be useful if there was an API to dynamically setup the guest network (for example with a password that changes every week or something). Some routers might have that.

Otherwise, besides the novelty, I don't see a practical case when this solution might be better than a printed QR code?

Hi HN,

I used a Raspberry Pi Pico with a screen to join a Wi-Fi network with style :)

Detailed instructions and a few tricks available at https://github.com/predmijat/qr_wifi

I hope you like it!