App Clips rely heavily on in-person experiences. It came out just before the pandemic hit. Apple should reintroduce them when this is all behind us.
That said, I came across App Clips frequently in New York. Restaurants, coffee shops and museums use them. Great experience, for example booking a ticket and time slot at the Museum of Natural History, without having to download the app. A diner in the financial district had an App Clip that enabled me to pull up their menu and order breakfast before being seated. My food arrived quickly after they seated me. Great use of the tech.
I could see a combination of Live Activities with App Clips where you're on your way to a take out restaurant, Apple Maps shows the App Clip, which when opened shows the menu without downloading an app, then you order and it turns into a Live Activity showing you the status of your order. When it's ready, you'd see a Pick Up status with your name that you can show to at the counter and walk out with your food.
There are so many one time use apps that we have on our phones for when you'll maybe need it again. It's a bad experience. App Clips with Live Activity makes much more sense and I hope it replaces many apps we use today.