I've never seen it either and it seems like this is very difficult to make happen. buying soda or snacks with bitcoin or popular crypto such as ETH or BNB is very difficult to realize because the prices fluctuate and there are still few people who know about crypto. buying things with your favorite crypto is much more difficult because it is likely that everyone's favorite crypto is different.
Yes, there will be a difference in the preferred currency for users due to gas fees during payment, and as you know, there are many networks that provide different options, so machines that accept different networks for payment will be distinguished from others. I think Bitcoin lovers will love paying via the LN.