Proton Chain is an open source project, below are important Github repos to follow.
Join the Official Proton developer channel on Telegram. https://t.me/protondev
The blockchain that interacts with fiat. https://github.com/ProtonProtocol
Kotlin library for handling Proton Chain operations. The main purpose of this library is for account and key management, but also handles signing and pushing transactions. https://github.com/ProtonProtocol/ProtonKotlin
Proton is a drop in library to handle all things ProtonChain. This includes but is not limited to accout management and storage, signing and pushing transctions, etc https://github.com/ProtonProtocol/ProtonSwift