Can I see if devices are being used?

The best I can see, where your are logged into and on what devices.

It will not record when if was last used

Check your Apple ID device list to find where you're signed in - Apple Support (CA)

The above or use the " Find My " application in Applications folder

1. This is the iMac(Power PC) forum, for very, very old Macs. If your iMac us running macOS 12, its not a PPC Mac.
2. No, there is no usage history anywhere for devices.

getcodesign wrote:

Is there a record of my devices to see if they were used in the past few hours?

Why?