I understand this question might not be entirely appropriate for this forum and that I should try Stack Overflow instead, but I think it may be a concern others have faced and solved before (tiny SaaS grows into a large company, large enterprise customer wants an on-premise distribution of application on air-gapped network, SaaS updates build pipeline to support offline distributions).
https://classic.yarnpkg.com/blog/2016/11/24/offline-mirror/
https://blog.isquaredsoftware.com/2017/07/practical-redux-pa...