Without indicating my personal feelings on monorepo vs polyrepo, or expressing any thoughts about the experience shared here, I would like to point out that open-source projects have different and sometimes conflicting needs compared to proprietary closed-source projects. The best solution for one is sometimes the extreme opposite for the other.
In particular many build pipelines involving private sources or artifacts become drastically more complicated than their those of publicly available counterparts.
I've also seen this with branching strategies. IMO the best branching strategy for open source projects is generally the worst one for commercial projects, and vice versa.
In particular many build pipelines involving private sources or artifacts become drastically more complicated than their those of publicly available counterparts.