Following the official launch of the Steam Frame, Valve has made Lepton, its compatibility layer enabling the device to run Android games, open-source. The project is now hosted on Valve's GitLab repository. Lepton was formally announced in March 2026 alongside the Steam Frame Verified program requirements.

Valve states that Lepton is intended to help game developers bring their VR Android games to the Steam Frame, noting other use cases are possible but were not the focus of development and may lack polish. The tool uses components from Waydroid, Anbox, Halium, and Hybris, combining Valve's own code with parts of the AOSP. It mounts host system libraries—graphics drivers, Steam libraries, and Vulkan layers—while stripping away unnecessary Android components for efficiency.

The open-source release implies developers may utilize Lepton's code directly or adapt Valve's implementation for other applications, potentially forking it to add features or optimize performance, similar to community forks like Cachy OS-Proton and Proton-GE.