I wouldn't call it passive.
The $ZKF is it a coin or airdrop? Op let me tell you there are earning that one will make in internet that is not even worth it.
There is airdrop: if you used lomoz (never heard about it before), polygon zkevm, zksync, you are eligible, claim will open soon, and there are campaigns that you can do to earn oats, nfts and stuff.
All these can be found from sidebar on their website:
https://zkfair.io/