Android Oreo is already out for the selected devices. Recently launched Google Pixel 2 and Pixel 2 XL also come with Android Oreo out of the box.
In terms of the MIUI interface, its latest version named as MIUI 9 is based on Android Nougat. The company has announced the ROM back in July. Since only beta/developer ROM is rolling out for the devices.
The reality is Xiaomi devices or MIUI powered devices will get Android Oreo after a long span of time. Grab this Android Ore Stock Ringtone Collection while waiting for Oreo.
The file comes in a ZIP file. Download the ZIP from the above link and extract it in order to get the files. You will find 10 stock ringtones.
You will like the collection. The ringtones collection includes- beats, dance party, shooting star and some more cool ringtones.