The easiest thing everyone can do is when they are cashing out, simply ask "may I pay using the bitcoin lightning network?"
If customers don't ask, businesses jave no reason to start.
Now you also have to be ready to spend... which most folks aren't.
If you can’t find a restaurant that accepts payment in BTC, try to get a restaurant owner who would be interested in crypto. If you happen to find a Bitcoin enthusiast they would totally love to get funded through a pizza delivery. I think that will be the best way to celebrate Bitcoin pizza day.
Welcome to every day of my life.