There are many things you can do with HEART! Stake them into Land of Love, to earn more HEART emissions and LOVE tokens. This works the same way as earning "interest" on bank deposits in Metanoia's staking program. Use them to purchase PowerUps for Mixies, these can come in the form of Potions, Scrolls and Food, which makes Mixies powerful and grant you more rewards.
Create proposals and vote for proposals in the Metanoia governance ecosystem, with 1 HEART token representing 1 vote in the ecosystem.