until now im just only know 2 way for earn crypto without invest and mining, the 2 way itself was through bounty and airdrop, but mostly program now neither bounty or airdrop was fake and scam.
Be carefull to see bounty or airdrop is scam or not.
I think now do airdrop is difficult to join like Blockchain and Coinbase earn.
You need to do KYC then join whitelist. This is take long time to check our airdrop is approve or not.