Based on my research, the Vivo Y17 (4/64GB) was launched in May 2019 with a price range of around PHP 12,999- PHP 13,999 brand new. Since your friend has had the phone for 4 years and it is still in good condition with no scratches or repairs, the resale value may vary depending on the current market demand and condition of the device.
In Cebu province, the estimated resale price for a 4-year-old Vivo Y17 (4/64GB) in good condition ranges from PHP 4,000- PHP 6,000. However, the actual price may still be negotiated between the buyer and seller. It is also recommended to check the current market prices and condition of the device before selling it to ensure a fair price.
Additionally, your friend can consider selling the phone online through various platforms such as Shopee, Lazada, or Facebook Marketplace to get a wider reach of potential buyers.