Who is using this with the App Router? Or is there a nice alternative out there?

https://www.npmjs.com/package/nextjs-progressbar

/new-york by day 🗽 /zinger by night 😈 Fan of eating tacos and bringing people together, often at the same time 🌮

Use case is indicating that a route transition is in place. Would be nice to have some feedback for the user given the transitions are not quite instant.

What's your use case? I would say packages like these are largely unnecessary today with things like prefetching and prerendering