Reopening this discussion and answering my own question from this thread.
As I understand it: What makes Venmo and others like CashApp successful?:
- A contact book and user IDs. When joining Venmo you can import your contacts and get your own Venmo ID. Not something I would recommend for Grin to do, but instead we could use integration with Nostr, you can import people their Nostr IDs. Also, nothing is stopping users from sharing QR codes with a payment request or offering to pay a contract via other media such as Signal. That is basically what I do with a local payment APP in my country for easy bill splitting. This is done via sharing a link/IRI that goes to a central server which triggers opening of the Venmo APP. Perhaps we can use the deeplink-system that allows opening of a wallet APP from a Grin QR payment request qr code. Using depplinks should trigger opening of the wallet APP independent from which media channel is used since the URI/IRI as link or as QR-code triggers the opening of the wallet AP via the browser.
- Payment requests & Payment offers and bill splitting. I see this matches quite nicely with terminology from contract flow payments. Splitting of a bill to keep track of who paid a ticket and who did not might require a bit of extra wrapper metadata which touches on many discussion we had on putting slatepacks in an optional wrappers that can contain extra metadata. By including some extra metadata like payment request ID and user ID, it should be very easy to keep track of transactions that belong to a single split bill. As long as the content is encrypted for the receiver, their should be no information leakage when including extra metadata.
- Exchange integration? Topping up and easy on an off ramping of Grin might be what makes Venmo easy. Not sure if this is possible, it is not something we can direct but who knows, maybe TO is interested or Gate if we have a good wallet to support it.
- International payments. Venmo is from PayPal and such allows easy micropayments internationally although they take 0-3% fee on those payments via Venmo 0-5% for PayPall international payments. Grin does not have that problem at al, so potentially would be better as long as you keep your Grin as Grin.
- Mass adoption and acceptance… and that is something not so easy achieve. Even with the best designed APP and with exchange integration, the main bottleneck of any crypto currency is that not many people are willing to accept it. But then again, perhaps a great wallet APP might speed up adoption considerably.
@trab Anything I missed or got wrong? I based the information on what I could find out about Venmo online, I never used the APP.
Can anyone check how split bills work? I scanned a few online Venmo example QR codes, they only contain user ID’s, but I want to know what else they might include, such as amount in a split bill request, perhaps a request ID etc.
The biggest question remains if any developer is interested in implementing some or all of such features in their wallet. We can envision, plan, support as CC and as community, but only developers have the power to make visions a reality 
@i1skn @davidtavarez @ardocrat, does this anyway align with what you vision is for the wallets you work on for now or in the future?