GM I wonder what kind of confusion it would create if someone tried to attend an event like this without owning a smartphone

pre-paid in-person non-KYC sim (or KYC-free Bitcoin, etc), used device and IMEI, VPN, offshore secure email, de-Googled Android ROM, apk installs, and separation of use works

should take a polaroid of the ticket with qr code on the screen and bring that.