Missed this the first time around – happy to answer here.
The number of users or “instances of use” of your application are not figured in to rate limits for app-only auth. A method with a limit of 180 requests per 15 minute window is intrinsic to your application, regardless of whether it’s on device A, device B, device C, website 1, website 2.
The best way to allow your end users to access Twitter content in your app is to require them to auth and leverage their access tokens. Otherwise, you may want to think of a centralized setup where your application securely accesses your servers to retrieve data you’ve collected instead.