You can set a timer on the HomePod for a certain number of minutes or hours. You just say: “Hey Siri, set a timer for [amount of time].” If you ask Siri to set a timer for longer than 24 hours, she will suggest to use a reminder instead.
To find out how much time is remaining on the timer, just ask: “Hey Siri, how much time is left on the timer?” At any point you can turn off or the timer by saying: “Hey Siri, turn off the timer” or “Hey Siri, pause the timer.”
You can only set one timer at a time on the HomePod. But we can use Reminders as a timer workaround. Instead of setting a timer, just say: “Hey Siri, remind me to do [task] in [amount of time].” However, you can’t check the time remaining.
And of course, this can also be extended to iOS as well. You can manually set multiple reminder/timers, or use Siri to accomplish the same thing.