Basic computer logon tracking/monitoring tools?

Our mgmt has asked us to look into some employee monitoring software- we're in consulting and there are some users allocating 'problematic' qtys of hours accross multiple clients and ending up wiht nearly a 2nd FTE worth of hours in OT every month... for many many months in a row. Many of these people are PMs booking to their own projects. Since this isn't 'slacking off', the traditional response to employee tracking softwares (jsut get better managers/make sure work is being completed) doesn't work. Naturaly, mgmt wants to get some data to crack down on this because if the clients were to discover this may put us in a difficult position. They've asked us to look for tooling to grab all the 'active' hours of our PCs, however since we're using Azure AD Joined (not domain joined) machines, and many are located remote - AD logins aren't a useful/workable metric. We alreayd have SASE and DLP tooling for the actualy 'required' level of 'corpo spyware' - so we don't need screenshooting/web browser monitoring. Anyone got recomendations for a 'cheap and cheerful' SaaS option that can silently track times a company computer is unlocked/being used and has SSO/other basic enterprise app features.