I control my lights almost exclusively with Siri (very little lag, and the ability to turn on 4-5 lights at once, all to particular levels / hues, would take wandering around to multiple switches to do the same by hand and would be much slower). "Hey Siri, set ambience".
I use Siri to set timers and alarms (a common one is, put my Apple watch on the charger and say "Hey Siri, set a one hour 'put on watch' timer", to remind myself to put the watch back on).
I ask Siri to add reminders, which then get sucked into OmniFocus (there's a more complicated / newer way to tell OmniFocus directly via Siri, but it's so much simpler to just say, "hey Siri, remind me in the morning to take X with me" without a lot of extra syntax). I actually find this really useful, because it's easy to think of something you want to remember / need to do, and then have lost track of it a few minutes later, when the context has changed / something comes up - if I tell Siri now, to remind me of something tonight, it doesn't matter if I get distracted by something else five minutes from now - my phone will remind me tonight.
I occasionally check the weather with Siri - mostly for other locations (I built my own weather station a while back, and trust the temperatures and forecasts from that more, for my house - Siri can only tell me the outside temperature somewhere nearby, not on my porch - but Siri can tell me the temperatures in other parts of the city).
I have one mini on a high shelf in the bathroom, which I use for playing podcasts while in the shower / getting ready, and I occasionally tell it to remind me of things as well (trying to write something down / type something in, in the shower, would not be optimal).
I never ask my HomePod minis to play music (and occasionally shout "hey Siri stop!" when she misunderstands and starts cueing up some random song) - if I want music, I say, "Hey Sonos, play jazz" (or some other genre, or something more specific). Because Sonos makes a reasonable home theater system - I waited a year or two for Apple to do so, but they didn't (then ended up releasing some half-baked support home theater through HomePods, but only via Apple TV, and with other limitations - the Sonos system works great for TV / AppleTV / PS5, direct voice requests, and as an AirPlay target, and largely hits Apple's original slogan of Just Works™️).
