there are so many cryptocurrency which has low transaction fee like dogecoin,digibyte,bnb,dash but instead of all these coins I'll be prefer tron because it's transaction speed is much for faster than any other cryptocurrency
Well, yeah tron is a good option but I will personally go with XRP because the same address can be used by the owner with different tags which makes it easier and the confirmations are instant as anyone who uses ripple knows about it. I actually wonder if such ideas (as OP was made in 2018) ever came into existence and become a reality.
Honestly if I could walk into a store and pay them via scamming QR code via ripple then really would buy a few extra items or if it is a coffee shop them maybe 2 cups extra.