For sure this format does not allow for a lot of postflop play, but its free money, so we can either take it or leave it. And its not pure luck. With usually 6.000 people competing in the early event and 9.000 in the late, we can only expect to cash 1 out of 10-15 times. But by understanding and implementing the right strategy that number can surely be increased at least somewhat.
Basically you want to be very aggressive in these events, until you stack is large enough to cash, and then shut it down. Playing coinflips is actually desirable early on, because there is no difference between finishing as 8.221 or 843. So forget all about “ICM” and “surviving”, because it does not apply to this format early on. On the contrary variance is your friend, because it increase your chance of cashing.
So if several players have limped into the pot, and you look down at 66 with a 30BB stack in the blinds, dont limp behind, go all in! Its totally fine, if you get called by two overcards, and if everyone fold their nonsense, that is fine as well, because then you just increased your stack 20 %. Last night someone got mad at me for jamming over his limps several times, but this is not the place to practice your postflop skills.
When your stack is large enough to cash though, you should go in the exact opposite corner and usually just fold your way into the money. I have folded KK and even AA preflop is this situation, because winning more chips would give me zero extra value. Some people needlessly continue to play, even they dont have to, and sometimes you will cash at the cost of them, so this is also an area, where you can find edge.
And finally, as you say, some players are not even sitting in, so you gain edge by just being there and not getting blinded away.