Whether it’s converting fiat to bitcoin or just simply getting a LN wallet setup to zap, it’s not straightforward unless you already know what you’re doing and already have some sats. Primal is currently the easiest with the built in wallet, but also their wallet is not available everywhere. And since most people in the world don’t already have bitcoin, they for sure don’t have any of it to spend on tips. Everyone has fiat though, so making it easier to bridge between fiat and bitcoin via zaps would be huge.  

 I was going to mention Primal, and as I went to the screen to try to convert fiat to ₿, it states, "primal store sats are not available at this time."