Heating with an electric heat pump is quite efficient in most environments. Electric resistance heat is inefficient.
Electric resistance heat is inefficient but it's a plug-and-play replacement solution for gas heaters. You can directly replace it without any changes to the home other than needing an extra circuit breaker and wire pulled.
Old ones maybe. We've installed a Mitsubishi mini-split that can heat a 1900 sq ft. mediocrely insulated home in Appalachia (this morning was -6C). Never mind, the indoor spits (<30dB?), the compressor outside is so quiet you can't hear it if you're next to it. My, brand new, radon pump is far noisier.
As to footprint, the compressor is tall and wide (about 1m). But it's only 25 cm thick, so it doesn't take much room at all along the wall.
Really, Europe has no reason at all not to go all in with splits.
Even the "quiet" new ones cause a problem when placed in the confined area between buildings[1]. It projects low frequency noise into the neighboring structure. Very hard to deal with. You still need to be careful with placement[2].
[1] http://www.quiet.org/readings/a-c_sound%20advice.htm
[2] https://www.eugene-or.gov/DocumentCenter/View/17196/Neighbor... (PDF)
Also split units are rather ugly and with older homes you ruin the look. Government hot water heating with city water is much better as it doesn't affect how the street or homes look like.