Adding coordinates in different CRS to attribute table with PyQGIS

Question

I have a point layer in EPSG:23700, but I want to save coordinates into the attribute table in a different CRS (EPSG: 4326), without transforming/changing the layer (I want to keep it in EPSG:23700).

I would do this in Field Calculator:

x(transform($geometry, layer_property(@layer_id, 'crs'), 'EPSG:4326'))

Is there a way to do this with Python?

Btw. I am saving the original coordinates with this simple code (I want to extend this):

layer = iface.activeLayer()  
selected_feature = layer.selectedFeatures()  
layer.startEditing()  

for feature in selected_feature:  
    feature["EOV_X"] = feature.geometry().asPoint()[0]  
    feature["EOV_Y"] = feature.geometry().asPoint()[1]  
    layer.updateFeature(feature)  

layer.commitChanges()

Answer 1

Add two fields for "Latitude" and "Longitude" and use the following script. It utilizes pyproj.

from pyproj import CRS, Transformer

layer = iface.activeLayer()  
selected_features = layer.selectedFeatures()

layer.startEditing()

tr = Transformer.from_crs(CRS.from_epsg(23700), CRS.from_epsg(4326))

for feature in selected_features:
    
    x = feature.geometry().asPoint()[0]
    y = feature.geometry().asPoint()[1]
    feature["X"] = x
    feature["Y"] = y
    
    lat, lon = tr.transform(x, y)
    feature["Latitude"] = lat
    feature["Longitude"] = lon
       
    layer.updateFeature(feature)  

layer.commitChanges()