Thank you for your follow up.
I am sorry to hear about all the trouble that your son is in.
Basically, the US Constitution
does guarantee a right to legal counsel / lawyer for a defendant who is charged with a crime which can result in a any type of jail / prison sentence and your son does have the right to request for a public defender to be appointed to him, if your son cannot afford a private local criminal defense attorney
Unfortunately, it is your son that has to make the request and demand to have a public defender appointed to him and because your son is of legal age and is a competent adult, you would not have any standing to make such request for a public defender on his behalf.
The only thing that you could do is contact a local ND private criminal defense attorney and if you can afford the services of a private criminal defense attorney, then you would be able to retain such local attorney to represent your son.
Unfortunately, GSI with a minor is a strict liability offense, which does not require intent or knowledge of the age of the victim by the defendant and all that the state has to prove in order to convict your son, that the victim was a minor and your son did commit a sex act with the victim.
Unfortunately, your son has been charged with an extremely serious crime and the maximum penalty for such class A felony is up to 20 years in prison and a fine of up to $10,000 upon conviction.
I wish you and your son the best of luck!