I am working on https://www.usertrack.net, but tracking currently only works per domain, I assume your user listings are at a specific path? You can contact me via the contact form on the site to discuss integration options or how to separate the stats per user instead of per domain.
Use an open source analytics solution like Matomo (fka Piwik) and make some custom views of the their MySQL (technically MariaDB) database that returns data for the specific customer.
I am working on https://www.usertrack.net, but tracking currently only works per domain, I assume your user listings are at a specific path? You can contact me via the contact form on the site to discuss integration options or how to separate the stats per user instead of per domain.