Answers
According to the relevant provisions οf immigration law in force, the investor must have full ownership and possession of the property at the time of submitting the permanent resident application, and the existence of a mortgage constitutes an obstacle to this condition. After the issuance of a resident permit, the investor may obtain a loan in Greece or anywhere else, with a mortgage on the acquired property, under the related terms and conditions of each bank. In all cases, the price of the real estate has to be paid via a crossed bank check or through a banking transaction from the Greek bank account of the buyer to the Greek bank account of the seller. So a loan can be taken from your bank, provided that no encumbrances, hypothecs, etc., are on the property. If your bank could provide you a loan with securities beyond the under purchase property, there is no obstacle for the Golden Visa procedure.
You need to have the full amount of 250,000 euros (as needed for Golden Visa proceedings) for the purchase of the property at the signing date and not after that.
The money has to be from a source abroad.