Yes, but he explicitly makes weapons. New Yellow Devil probably would be equal to Sunstar or Duo, since Ra Moon veiwed it as a perfect machine. Not to mention if Sunstar is 5-B and Mega Man defeated him. And it's not really that much of an outlier. Small Planet+ isn't far from Planet.
Sunstar is At least Low 5-B, likely 5-B through scaling to satellite lasers and Composite Mega Man is solidly 5-B through scaling to him / satellite lasers while also being scaled to him in his base form...?
Like, I don't know why Sunstar has the 5-B stat straight-up but Mega apparently only scales in composite. I'm having a bad time at wording things right now but
No. Sunstar is Low 5-B due to shaking the Wily Star during his fight with Mega Man. Only the composite version is scaled to Satellite Lasers, given that the Satellite Lasers don't exist in the main canon, but are still inferior to Ra Moon's creations.