Solend, the project I founded, did this with "Points Season 1," where a minimum rewards pool (which could only be increased) was disclosed and a timeframe was communicated. The rewards pool started with 100,000 SLND tokens and was later increased to include 100,000 PYTH (the governance token for Pyth Network) and 10 Tensorians (the NFT collection launched by Tensor, the leading NFT marketplace on Solana).
