Terrible to see that. Any recommendations on a reliable CO detector to travel with?
Just grab one from a wall in your home. I hope that you have one in each bedroom. I think that they are all small and lightweight enough to be insignificant in your checked bags. Just make sure it's the first thing you unpack at the hotel, then again when you get home.
If you want one dedicated to travel, there are dozens of choices these days. Get one that detects CO and Smoke both. Walmart for example lists a couple hundred, but you would need to shop the details. The cheaper ones are unknown brands from overseas while Kidde and First Alert are the leading US brands even tho they are made overseas. Those cheaper models probably work ok, but I hate that most use AAA batteries - a personal objection of mine since I think that anything built with AAAs could have built to use AAs that have so much more reserve power.
I travel with a small
Inspector (CO) INS2-CO-01 hung on my backpack as I enter the airport and go thru security, still there on the plane since none have their own CO alarms, then in my room until I leave for a dive, then used to check my tanks using a gallon ziplock. But then I take it everywhere as I know that most stores and even restaurants don't bother keeping one active. For important accuracy needs it'd need to be calibrated periodically, but for our needs - they have software that adjusts for sensor drift enough to keep us safe. Leave it on 24x7 and the battery will last at least a couple of years. Two years ago I bought a new one on sale instead of sending my old one back for biennial battery and sensor replacement, left the old one on to see how long it'll last, and it's almost to four years now, still working.
The problem with CO alarms is most are impossible to test. I'll take my smoke alarms out on my driveway in the fall along with a fire extinguisher, a metal coffee can, and rags and test them to confirm that they respond to smoke. Home CO alarms cannot be tested as they're designed to go off only at dangerous home levels, so all you can do is test them monthly and keep the batteries up to date, so I keep several even tho I live alone. Sensorcon CO alarms can be tested in a closed garage with a car and remote start, but that's risky. Be careful if you do.
By the way, today is the first of the month, the day I suggest everyone tests their Smoke and CO alarms. Push those buttons and check those batteries.