Or we could answer the question right here, to build our own body of knowledge:

Google says it’s releasing its brand font into the wild to avoid fragmentation and allow developers and designers to “bridge the visual gap between first-party and third-party apps”.

It notes that until now, you might see Google Sans in Gmail, then open WhatsApp and see Roboto or a device-specific font. It sees that as a “persistent, if subtle, point of friction”.

This fragmented visual language, unlike the unified font experiences on some other platforms, has prevented a seamless digital experience. “It just doesn’t feel as nice,” stresses Visual Designer Megan Lynch. “On a subconscious level it impacts the experience.”

By making Google Sans open source, it hopes to allow UI designers in particular to craft a more unified experience across devices and platforms with clear, comfortable interface designs.

Source