It's also something I am thinking about a lot.

I think especially in countries where the currency hasn't yet collapsed, merchants are mostly motivated by boosting their sales, so the first obvious step would be asking to pay with lightning as much as possible.

Another area I noticed where lightning can shine is for small payments. For example I noticed many food trucks currently accept cash only payments, because credit card companies charge something like 1.50 CHF base fee plus 3% commision. With lightning the fees would be negligible and the payments tend to be pretty fast and with no issues for small amounts.