Sure, you can use lights and smart plugs to turn your appliances on and off to give the illusion that somebody's home — or, you can tap into the market of smart locks and cameras.
Smart doorbells let you monitor who's coming to your doorstep even when you're not home, using a camera and an in-app calling feature that uses two-way audio and one-way video.
When the doorbell rings, your phone calls you with video. You can answer to talk or ignore the call completely, and if the app is synced to a smart lock — a deadbolt controlled via app, or with a smart speaker using a PIN number that you say aloud — you can even let them in. The most popular smart doorbells use motion sensors to notify you when someone's at your door and let you replay footage.
Since it's such a broad category, manufacturers of security devices tend to focus on different home security devices:
Ring doesn't make locks but it does have a good variety of home-security devices, including fire alarms. Its devices are also compatible with the three big smart assistants, despite having been recently acquired by Amazon.
August makes locks and doorbells, and is also compatible with the three big smart assistants.
iSmartAlarm's in-home security cameras are also popular, but only work with Alexa right now.