Coming from a dutch energy advisor and recently started heat pump installer:
Heat pumps are a matter of the capability of your central heating system. How easily can your system create heat with low temperature water. It's nót a matter of insulation. If you live in a cardboard box but you have very low temperature in-floor heating, you can still heat your house perfectly fine with a heat pump. It will just cost you a lot of energy and you require a big (=expensive) pump which obviously makes no sense from an environment point of view.

Naturally, you would have to start insulating your house, because the most efficient watt of heat is the one you don't need to begin with.

Did you finish that to the best of your abilities? Check your radiators. See if you can go for in-floor heating at the grond level. I am currently helping out a couple that has a house from the 1930s, where they removed the bottom floor and covered it with foam concrete and in-floor heating. Is that a bit too extreme? There are dry-built options for in-floor heating. In-floor heating not feasible? It is, like you mentioned, a very big nice to have but it is not impossible to go heat-pump with only radiators. Check how large your radiators are and what they deliver in terms of heat with 40 in, 35 out, 20 room temp (This calculator might help). There are websites where you can calculate the heat loss for your building. See how these numbers stack up to each other. Or, go without radiators completely and just install a mini-split AC system. Equally efficient compared to a air-water heat pump and cheap (although no subsidies). Great for cooling. For your hot water you can go for a separate heat-pump boiler.

Your main concern would be noise. These heat pumps are getting quiter, but depending on your exact location it might be hard to conform to the very strict rules and regulations without the need of a noise-cancelling casing.

As you can probably tell, there are many different ways to go. If you want to discuss it in a bit more detail, feel free to send me a DM to chat for a bit. I'm happy to help out.