They're pretty solid cars. Unfortunately, there's not much warning before a major component like the battery or inverter dies, so checking for codes and CEL is about all you can reasonably do to check the hybrid systems. One thing to be aware of is that they like to start using some oil around ~100k miles. Because of that, I'd value lower miles over newer in the hopes that it hasn't been run dry. I believe the 2010s had a couple issues that were resolved in the following years, but I don't think it was anything major.
On the test drive, the battery shouldn't go from full to empty or empty to full very quickly unless you're blasting the AC and driving it hard while it's warming up or going down a long, steep hill. You also shouldn't be able to hear the battery's fan in the back right 99% of the time. Either of those can be a sign of a weak battery.
If you have an Android device and an OBDII reader you can connect to it, the Hybrid Assistant app can show you what's going on with the car. There's even a battery testing mode that can help determine the battery's health. I did a little review of the app
here.