Is a comparator the correct part to choose?
So basically:

Vin &lt; 0.8 V: 1

Vin > 3V: 0

Supply is 3.3 V

You don't need a comparator for that, a simple inverter in a 74HC04 can already do that. Look at the 74HC04 datasheet

Unfortunately low and high levels are not listed for 3.3 V. But lets look at the 2 V values. 0.8 V (or lower) is typically assumed to be 0 and 1.2 V (or higher) is assumed 1. At 3.3 V supply voltage these values will increase somewhat which is beneficial for your requirement.

Another bonus is that one 74HC04 contains 6 inverters so you can monitor 6 pins !

A CMOS inverter is one of the simplest and cheapest circuits available so I doubt that there is a simpler and/or cheaper solution.