Can I track HTML5 web pages with unknown website URL?

I want to track usages of a HTML-based application whether it is installed on a mobile or desktop. The app is run locally but connected to the Internet. Some unknown devices might use this application, therefore there is no website URL to be set while defining a new website on the Piwik server.
Since the website URL is a mandatory field in creating a website in the Piwik administration panel, I had to use some fake URLs in defining a new website monitoring. I expected that when I insert the the Javascript tracking code on the webpages with the tracker URL (the url of the Piwik server), requests from the webpages are received by the Piwik server, but in reality it is not. Is there any setting that bans requests to the Piwik server? Is there any way to monitor such HTML-based applications without a defined website URL?

Piwik should track the request as you expected. do you see an error in brower console? See also: Piwik doesn't track any visits and pages, and shows "There is no data for this report" in all reports. - Analytics Platform - Matomo