There are 2 repositories under decentralized-federated-learning topic.
FedML - The Research and Production Integrated Federated Learning Library: https://fedml.ai
All materials you need for Federated Learning: blogs, videos, papers, and softwares, etc.
Fedstellar: A Platform for Decentralized Federated Learning
SWIFT: Shared WaIt Free Transmission
Decentralized Sporadic Federated Learning: A Unified Methodology with Generalized Convergence Guarantees