Very strong vape. Actually, really asking for a friend

He is 60 and has been smoking since he was five. He currently has a nic salt vape, says it isn't strong enough to replace a cigarette; he wants to be able to smoke indoors. What would be strong enough to replace a cigarette? and of course, if it would help him quit he would be ecstatic. I should probably ask for the strongest vape there is; would that break the bank? All advice welcome.

PS I help him with searches due to a slight vision issue.