How to label the sum of a field in another layer based on proximity

Question

From two layers with point geometry, I use the following expression to draw a line from the 'POINT_LAYER_2' layer to the 'POINT_LAYER_1' layer.

make_line($geometry,overlay_nearest('POINT_LAYER_1',$geometry,limit:=1))

The layer 'POINT_LAYER_2' contains the numeric field "HOUSES" representing the number of houses.

I would like to label the 'POINT_LAYER_1' layer with the sum value of the "HOUSES" field of the 'POINT_LAYER_2' layer corresponding to points connected.

So far I only manage to label the sum, but on the layer 'POINT_LAYER_2', with the following expression:

sum("HOUSES", group_by:=overlay_nearest('POINT_LAYER_1',$id,limit:=1))

What I would need to get is an expression that works on layer 'POINT_LAYER_1' with the following result:

I have tried another approach, but it still does not give the expected result, as it shows the total sum value without filtering the nearest point:

aggregate(
    layer:='POINT_LAYER_2',
    aggregate:='sum',
    expression:="HOUSES",
    filter:=touches(make_line($geometry,overlay_nearest('POINT_LAYER_1',$geometry,limit:=1)), $geometry)
)

Answer 1

If you have a unique ID in POINT_LAYER_1, you can do it as follows:

Create a virtual field in POINT_LAYER_2 with the ID of the nearest object of POINT_LAYER_1:

overlay_nearest('POINT_LAYER_1', "id" ,limit:=1)[0]

Create a virtual field in POINT_LAYER_1 with the sum of all objects of POINT_LAYER_2 with the corresponding ID:

aggregate('POINT_LAYER_2', 'sum', "HOUSES", "POINT_LAYER_1_id"=attributes(@parent)['id'])

The virtual field in POINT_LAYER_1 can then be used for labelling.