GitHub does not support this the AS/400 (aka IBM i, iSeries, i5, etc) out-of-the-box, but a vendor named Eradani has built software package to do exactly this. The product is called iGit (a function of Eradani DevOps) that allows for any Git-Based Tooling (like GitLab, GitHub, BitBucket, AzureDevOps) and also lets you do Pipelines (iBuild) and Deployment (iDeploy). There are plug-ins for RDi and VS Code, and robust PDM/SEU 5250 support for Git commands. The website is www.eradani.com