plenty of exchange offers sol flexible savings, there are also restaking protocol coming up in solana that imitates eigenlayer on ETH and such, but with $700 I guess your best bet would be airdrop and do some retroactive task so that you might be eligible.
current solana ecosystem is still on the making, most of defi already going big yes such as jup, raydium and so on but the other category such as staking protocol, l2 and so on are still on the way.
I think after ETH craze with its massive growth of defi, we will see solana massive defi boom basically repeating what happened to ETH.