Has anyone used Rosetta Stone or other apps to learn survival Greek?

Most of those platforms teach grammar and vocabulary as a foundation for actually learning a language. It sounds like what you want is just to learn some phrases, in their entirety. It’s a completely different approach.

I’d look for something like an ‘online phrase book’.

For tourist Italian, I got a set of language CDs and played them in my car while commuting. It worked pretty well. But I realize many new cars, like my current one, dont have CD players anymore. I got the CDs in a set from Sam's Club (!), but seen similar in Barnes & Noble. I've done Pimsleur, Duolingo, Babbel, and Rosetta for other languages, but as was said, they are foundational not conversational. I found it difficult to set aside consistent computer time for those online programs

Pimsleur is done primarily by listening. It‘s geared toward communication but it’s not ideal for „cramming.“ The recommendation is to do one 30 minute lesson daily. Also… I found that since the native speakers had not listened to the lessons, they often did not know how to respond to my statements „correctly“ 🙃.

My experience with free DuoLingo was that it was good for vocabulary but not so much for communication.

Are you planning on spending a lot of time in Greece or just on holiday?

It will take more than a few hours at the airport to learn much Greek.

You are better off learning a few words and phrases and that will more than likely be enough to break the ice with locals.

Most businesses and younger people speak English so you shouldn't have much problem communicating.

Unless you go to more rural and out of the way areas of Greece you'll find English spoken most everywhere else.

But as a show of respect do learn some basics like "Hello", "Thank You", "How Are You?"

One good phrase is "Do You Speak English?

Most guide books will have basic words and phrases you can quickly learn and I think that's the best way unless you are planning on staying in Greece for a long time.

I know five words in Greek. I didn't even need them since everyone I met in Greece spoke English. Or at least enough English to understand each other.