Hi Dread.
I'm not sure what his voice "really" sounds like, due to the Autotune.
If you have any vocal clips of him just singing without Pitch Correction, that'd be great.
Not sure if the nasality is primarily the Processing, or the current vocal situation. (hey I've been busted here too occasionally for being a bit nasal!

)
If the budget is around $3K, for a 10 year old...
For example, some of that $$ can go to regular voice lessons.
And since it's easily apparent he has an engaging personality, some for acting lessons too.
Is it possible for him to participate in local musical theater training for children?
Also as a "before" reference-when he's ready, could you record him in a good local Pro studio? I would keep the Raw recordings, along with the Processed ones.
Also they could try some different microphones, in a treated studio.
FWIW it's harder for me to assess any microphones, in a typical domestic situation.
(I'm testing a Premium vocal mic more tomorrow BTW)
Plus I don't have the years of ear experience, the strong AE's who frequent here do.
In "solo" I can (usually) judge a mic pretty well. But judging for the "Mix" is a lot tougher-ahead of time.
That's part of the reason you're better off having professional backup/expertise, as part of his "Team".
BTW most of the "Modern" vocal sound IMHO comes from the singer's tone itself. This is if you want the vocal to be more distinctive and natural. If a vocal is going to get tuned and hammered into submission, then how responsive the mic is to all that, is an important factor. In the "game of inches"... Yes it can be enhanced towards one end of the spectrum or the other via gear and processing.
Here's a vocal of mine done direct into my cheap cell phone.
But my voice seems oddly suited for Psychedelic type vocals, so I think it came out pretty well considering...
This was a "one take"/"off the cuff" vocal done on a park bench. No Autotune/just some kooky Processing for fun ala Bandlab.
Then a cool GS member surprised me, with added instrumentation as couple of months later.
I wasn't conscious I was following the timing of that song so closely!
My main point of the last paragraph, is finding what your son is naturally inclined towards, will help him discover his unique "real voice"... (so sayeth the Boomer Dinosaur here)
Chris