The UX trick to make this really take off will be physical cards that are PUSHABLE.
This CANNOT be done well purely with software.
Best option is something printable on STANDARD PRINTER so you aren't making people buy a printer (exception being that if you can print nicer card stock, it feels more valuable e.g. think heavy vs lightweight pen).
You can then get business card paper stock and easily make tons of physical Ln cash, and this could be used by every bitcoiner 100% of the time for tipping. Needs to be no more than $0.20 / piece of cash (offlinecashco nowhere close to being usable for tip for a single beverage in a bar for instance). Business cards well under this.
You could make a number of denomination cards so you can easily tip different amounts.
Something to solve: how do you keep track of which pieces you have handed someone to reclaim? -- I suppose if you have batches, just reclaim all of unclaimed automaticall 6 months later so you don't have to deal with tracking individually.
It's been something on my backlog that I will work on if it is not done by the time I have time for it (on roadmap for https://runcaliber.com).
NO OPT IN. I'm tired of trying to ask or pitch servers, especially if busy. We have technology. Human history is spoken, written, and now accounting language. Let's leverage technology 2 to get to 3, instead of just using 1. 1 QR code for funds, another for explaining bitcoin to absolute noob (or maybe embed the LN within website with unique QRs generated more similar to lnCash).
It's actually more compelling to just give people bitcoin without trying to convince them of anything.