Since Roboto, Google has been making its own fonts, some of which are better than other third party fonts. The still unnamed Google font may not cause the majority of the user's attention immediately, but those details have pointed out the difference, such as font end with curved edges rather than in a straight line way.
We will be "Product Sans" font typesetting for experts to judge whether or not good, but if you are curious to try, then you do not need to install Android 8.1 Oreo on the mobile phone in the preview, users do not even need to change the ROM to perform this operation.
However, you really need to import fonts using custom recovery software like TWRP. The process is different from device to device, but it usually does not require access to ROOT, and it needs to unlock the bootloader, which can still be considered as the failure of the user's mobile phone warranty.
The font has been tested, can be used in Android devices in the Lollipop and later versions of 5.x, and in MIUI 8 and 9, OnePlus, Lenovo and Motorola's official ROM and Lineage OS and AOSP test based on custom ROM.