Flying in and out of Germany on a soon-to expire Italian passport?

I'm an Italian citizen living in Germany and need to fly overseas. My Italian passport (the only EU ID document I have) is expiring within 2 months of my trip (South America) and getting it renewed in time is unlikely (I've already begun the process but it's probably not going to happen in time).

My main concern here would be if I'd be able to re-enter Germany under these circumstances? As I understand it, EU citizens can enter and leave any EU country up until the very day the passport expires, but I'm worried that something like this would cause issues with an airline or an airline worker in the South America country of departure when coming back (I'm a holder of a dual citizenship to the country I'll be traveling to, so entering said country wouldn't be an issue).

As I understand it, EU citizens can enter and leave any EU country up until the very day the passport expires

Correct and even if the passport expires, as per EU Directive 2004/38/EC, you are legally allowed to enter Germany if you can prove your identity and citizenship.

but I'm worried that something like this would cause issues with an airline or an airline worker in the South America country of departure when coming back

That may be an issue indeed, so be ready to show the rules (IATA/EU directive/etc.) to the airline check-in counter. You could also contact the local embassy if they're willing to give you some paperwork to help with the travel.