Reproducible builds and open source sounds like a good thing.
I wouldn’t expect the reviewers to deal with every add-ons bespoke snowflake build. Even less so if it requires access to a private module. Mozilla should provide a baseline of how a build is intended to be done, then extensions just have to follow this template. Though yes, you would expect them to have some familiarity with basic stuff like yarn and that the baseline supports a few of the most popular builders.
I wouldn’t expect the reviewers to deal with every add-ons bespoke snowflake build. Even less so if it requires access to a private module. Mozilla should provide a baseline of how a build is intended to be done, then extensions just have to follow this template. Though yes, you would expect them to have some familiarity with basic stuff like yarn and that the baseline supports a few of the most popular builders.