The only passive income apps that I know are all websites like VVS Finance (on Cronos ecosystem), Pancakeswap (on Binance Smart Chain), Algorand Governance Rewards, Midas Finance, and staking on the CDC app.
Since I have the 3% back in CRO rewards card from CDC ive been staking CRO for more CRO and ive been converting CRO to VVS to setup a couple of different tokens with auto compounding on the Cronos ecosystem.
Ive also been staking AVAX (17%) + BNB (11%) on Midas Investments. Oh and I also recently got approved for the Gemini Credit Card which earns me Bitcoin back on purchases. I find it easier to snowball my credit card rewards with crypto than the cash back rewards or gift card rewards credit cards because with those rewards I feel tempted to splurge on useless junk but with crypto back rewards credit cards it helps me stay disciplined and invest more into crypto by earning crypto rewards for my purchases.