Just look at China Wechat & Alipay .... we copy also failed big time.
Since its digital money, the QR code should be made available to all platform.
In small SG, we have so many payment app, but not interlink. GrabPay dont support PayNow
Google Pay not supported, all these hiccups should be address, include Visa/Master too.
So Tourist come to SG, no need money changer, just use their Bank App, scan & pay.