One good developer can start a shift but only if there's absolute buy-in from management (and you) to carve out the time the rest of the team needs to get up to

One good developer can start a shift but only if there's absolute buy-in from management (and you) to carve out the time the rest of the team needs to get up to speed. Since you say the current developers are also decent but otherwise inexperienced with the kind of work you expect there's a chance that with the right organisational changes and support (i.e.: allowing the experienced new developer to work more as a mentor than being responsible for deliveries right away) and given time those people could become more effective. The issue will land squarely on the engineering management though, they need to accept the current team is not up to par for the deliveries while not making them scared for their jobs (that would just make the current developers cynical, and doing whatever they can to claw back power before retirement). It's a long road ahead that requires a very competent engineering management team to pull off.