@pvonhellermannn we had this discussion as well.
Current heatpumps are much quieter than old ones.
We are getting an indoor version. It is the size of a fridge. Outdoors will just be the air ventilation.
I believe it will be as loud as a fridge.

Now our neighbours are fine with it.
(We are in an apartment building so had to ask hoa for permission)

There are also split heatpumps which will also reduce noise on the outside.

All the best for finding a good solution for your house!