May I share some criticism?
First off,I wanted to say that the clothes look amazing!The colors,the shading,everything!I think that you might've put a bit too many folds on the shirt,in places that clothes don't really fold.It's hard though,so I really can't blame you.I struggle a lot as well,just look at my submission!
The anatomy is quite good,but the fingers look a bit off.They seem like they're struggling to hold on to the waist and magnifying glass.On everything else,I think it's very good for a chibi style.
I think the biggest problem is with the expression.His mouth is a weak smile while his eyes look a bit sad.The eyes in general seem way too digital and detailed in comparison to the body.His hair is quite well thought out but I think it's better If you just do a blob of hair (if that makes any sense).It fits a lot more with the chibi style.
I also think that the background doesn't really work.The saturated outline clashes with the earthly browns and blacks of the character,and I think it makes it seem a lot less professional.I'd recommend having a blob of colour,pastel or dark,but try to stay away from highly saturated colors,with an outline that matches with the picture.If your blob is a dark color,you can also use white.
All and all, I think it's a very nice picture!I'm not a professional artist or anything like that,but I hope I helped you!I'm sorry if I said anything rude or hateful,I seriously want to see others improve and even if I don't use all of these tips,I have them stored in my brain for other artists.I'm like a walking criticism machine.
And please excuse any spelling or grammar mistakes,English is not my first language and I suck at everything ;0;