Is my understanding correct, that in an Electron application I have access to local files and therefore it is possible to read/write from/into a local JSON data file?
Yes, there is local file access.
The TElectronStringList could be a way to read/write this file as it has a SaveToFile(), LoadFromFile()
TWebClientDataSet.Rows is of type TJSArray
I can't use the helper methods?
LoadFromJSONFile();
SaveToJSONFile();
These methods do not exist.
Then you have different code completion than here