To use multi - chain ecosystems like Solana and Avalanche to expand airdrop coverage, first, understand the unique features and user bases of each chain. Develop projects or participate in activities on these chains that are attractive to their users. For example, on Solana, which is known for its high - speed and low - cost transactions, create projects that leverage these advantages. Build partnerships with other projects on these chains to increase visibility. Promote your airdrop opportunities across different chain - specific communities and social media groups. This way, you can reach a wider range of potential participants and increase the success rate of your airdrop.