How lending APY comes from

Lending APY comes from the borrowing interest rate that leveraged yield farmers pay for borrowing the assets from the lending pool to yield farm.
Whenever users deposit base assets to a lending pool, ibTokens specific to an underlying asset are generated as a representative of user's stake in the pool. ibTokens received are proportional to user's supply and accrues lending interest overtime. Once users withdraw assets from the pool, ibTokens are converted back to the base asset at an increased amount (initial supply value + lending interest). Learn more about ibTokens here.
Homora V2 is able to take leverage on many assets without having to bootstrap liquidity by partnering and integrating deeply with Iron Bank or Cream V2 as a source of liquidity. Read more about Homora V2 integration with IronBank here.