I completely redid it without reusing the hydronic baseboard. https://www.alpinehomeair.com/category/air-conditioning-cooling/ductless-mini-splits/four-zone-mini-split-systems

About $5k total including the tech coming out to charge it with refrigerant.

All the baseboard was rusted to heck and it’s nice to have the a/c now too. There are hot water heat pump options but i’d imagine they’re way harder to DIY. And much more expensive. https://www.spacepak.com/solstice-air-to-water-heat-pumps