If custom ROMs sound too technical, consider that the Oppo F3 is now over 8 years old. Hardware components (battery, charging port) degrade over time. The safest and most effective "Oreo update" is upgrading to a newer device like the Oppo F21, Reno series, or even a budget Oppo A-series, all of which run Android 12–14.
For advanced users who want a true Android 8.0 Oreo experience, the best option is to install a custom ROM based on Oreo, such as . This is the most promising path for getting a newer, more secure, and feature-rich Android experience on your Oppo F3. Oppo F3 Update 8.0 Download
Tap on to see if your current firmware (likely Nougat-based) has any pending security patches. If custom ROMs sound too technical, consider that