Local File read: whats the recommended approach?

I’m building my fiurst Observable charts. I need to read a (large) (java-app) logfile and search for inserted json metrics for plotting. I need to make this easy for users to deploy on their own machine to plot metrics from their own logfiles. Initally this is a static file; but the goal is to tail a logfile.
I’ve been building on MacOS/Chrome;but the cors protections seem to be a showstopper; for users that will have an enterprise blocker on changing cors settings. Is there a better approach to ingest a logfile for parsing by the javascript for the chart?