Dubias and calci worms are excellent, two of the very best. For treats you can include small hornworms, they are a little pricey and I'll warn you they grow super fast. If you get the smalls in a matter of a few days they may be too big for you little guy so I'd only get a small amount at a time. You can also include silkworms, butterworms and as occasional treats waxworms. Once he's a little bigger you can try out small superworms as treats too. I wouldn't use the supers right now however as they can be a little hard for babies to digest.
He looks very healthy so whatever you are doing I'd say keep it up. a few Dubias and calci worms may just be enough to fill him up right now which is perfectly fine. And the fact that he's already eating his salad is mind blowing! My beardie needs to take notes from your little guy lol