Just make sure you're comparing apples with apples when talking about "an 8kW heat pump" - if 8kW is it's heat output then it's electrical input will likely be a third of that or less; less than a fast kettle.
Even if the electrical input is 8kW (which would make it's heat output around 24kW, which is fairly monstrous in HP terms), it'll still run easily off a single phase setup, using commonly available cable diameters - you can buy electric showers that are more demanding
3 phases would give you a 22kW EV charger, but this isn't the full story; very few cars on the road will accept a full 22kW AC. If you bought a DC charger you might well get 22kW charging, but the prices of DC chargers are insane..
Suppose you had sn EV that did accept 22kW, and also had an 88kWh (an uncommonly large battery size for an EV) battery - it would notionally charge from 0 to full in 4 hours (actually a little longer, as they slow down as they become full).. be really honest with yourself re your driving habits though - do you really drive so much that you could only spare 5 hours to fill your Jaguar I-Pace every dsy? (note; an ipace doesn't accept 22kW, a Renault Zoe will and with a 50kWh battery is 2-3 hours charge but again, do you really need the speed?)
Mostly when people set out on the eV ownership journey they frame it in terms of what they know about fossil cars; fill ups are a 10 minute process at Asda on the way home and the lead assumption is they have to have a way of recharging their EV quickly. Mostly it's nonsense; perhaps valid for taxis driven by two drivers on shift, but regular people leave their car stationary outside their house for far longer than they drive it and as such even a lowly 3kW granny charger can suffice for a considerable cross section of users, let alone a 7kW single phase AC wall box