Are you aware of documentation that shows its possible to do what you ask?
I suspect that you’re budget is off by a factor of ten. It is a $50 to $100 job to see if it’s even possible.
There could be some way that’s easier than i can imagine, but you’ll need to do the work to figure out how to solve the problem first.
One solution that might fit your budget would be to have users use keybase to prove their connection to both your forum and their Xbox profile and then link to that somehow.Darn. I don’t see an easy way to do that either.
Aha. Here’s the API documentation: Universal Resource Identifier (URI) reference - Microsoft Game Development Kit | Microsoft Learn