Hey  nostr:npub1wmr34t36fy03m8hvgl96zl3znndyzyaqhwmwdtshwmtkg03fetaqhjg240, what Marko said above is correct: you can pay lightning invoices or send to any lightning address using Primal Wallet. 

HOWEVER, we do have a known bug in our iOS app where if you scan a lightning invoice of zero sats, the app doesn't give you an option to enter the amount. I presume this is what you ran into. 

Should be fixed in the next public build.