For the Northeast US (the largest heating oil market in the world), there isn't any kind of heat pump isn't going to work with existing forced hot water heating

For the Northeast US (the largest heating oil market in the world), there isn't any kind of heat pump isn't going to work with existing forced hot water heating systems which is by far the most common type of install. The heat pumps don't put out enough volume of water at a hot enough temperature (heat pumps at maybe 125F vs 185F for oil/gas boiler). Most radiators / baseboards will radiate about 650BTU/hr per linear foot at 185F and are sized based on the heat loss calculations for the room/house and the ASHRAE design temps for your location. So if a room needs 6500 BTU/hr at 25F outside to maintain 70F inside, then you'll need 10' of baseboard. If you start feeding 125F water instead of 185F water, then you'll get significantly less heat out of the rads/baseboard and you won't reach the design temps indoors unless it's much warmer out. Generally heat pumps (ground or air source) are forced hot air (since you only need to raise the air temp by a few degrees as long as you have enough CFM of air flowing), or radiant slab where you only need 75-80F water or the slab cracks and/or is uncomfortably hot. A combination of both also works as a radiant floor doesn't help with cooling in the summer. If you've got an existing forced air heating system, or are building a new house with forced air then either a GSHP or some of the newer air source heat pumps are a fantastic idea (despite the somewhat premium price vs a traditional oil/gas/propane boiler). Note that for GSHP it'll probably cost you upwards of $15K for the artesian well alone, but maybe you need one anyway (or already have one) if you're not on city-water in which case the only additional cost would be a variable speed pump vs a fixed speed one (assuming that the well is deep enough and has a high enough flow rate to provide enough "tons" of heating/cooling). Finally, not every city or town will give you a permit to drill a 600+' well (assuming the geology supports either an open or closed loop system). ... and you still need a heat source for domestic hot water, probably an on-demand natural gas/propane unit or an electrically heated hot water tank, although the GSHPs have a "de-superheater" feature that lets excess heat be diverted into the h/w tank during the summer/shoulder seasons, but generally not the winter. ... and the GSHP usually needs a backup heater (often resistive electric coils, but a smart design will use a hydronic coil on a zone on a condensing combi-boiler if you have one for hot water). The air source heat pumps definitely need a backup heater as they periodically run backwards to defrost the coils in the winter to prevent ice buildup in the condenser.