The product doesn't support custom fonts.
The reason for this is that each TV app/device is different in terms of if they allow custom or bespoke fonts. We therefore keep things consistent across our suite of apps.
Generally logos and colours are what users associate with brand identity so the font doesn't impact how lovely and recognisable the apps will be to them
As a general rule we use the native font for each of the devices. It can vary from device to device. On the web we use Open-Sans. This font is also the native font on some of the TV devices.
Updated about 1 month ago