Noah, who was 14, was found dead in a storm drain in north Belfast in June 2020, six days after he went missing.
His mother Fiona has already lodged a complaint with the Police Ombudsman over the way officers investigated her son's disappearance and death.
A crowd of about 200 people attended the protest in east Belfast.
During it, ACC Bobby Singleton of the Police Service of Northern Ireland (PSNI) accepted a petition demanding full disclosure from the Donohoe family and their supporters.
During a preliminary hearing at the inquest into Noah's death in December 2021, counsel for the PSNI indicated it would be likely to request a Public Interest Immunity certificate (PII certificate) on what it called a "limited amount" of material in three police evidence folders.
Speaking at the protest, Fiona Donohoe said: "Whatever it says, for Noah, we need to know - we're not going to give up."
"We will try everything to stop this
public interest immunity going forward," she said.
Image caption,nPart of the protest outside PSNI headquarters in east Belfast on Friday
The campaigners believe that decision on whether to apply was to be taken on Friday.The PSNI has said no decision has been taken.
Noah's family and supporters have been demanding to know details of the evidence which could be held back from the inquest.
In the past, the police have used PII certificates to protect the identity of informants.
However, they can also be used more routinely as a way of protecting sensitive details of their own operational methods.
They are commonly applied for, and granted at inquests.
The PSNI has not indicated what its reasons for applying might be.
If the police apply for a PII certificate, the decision on whether to grant one lies with the coroner, Joe McCrisken.
South Belfast SDLP MP Claire Hanna and Strangford DUP MP Jim Shannon have written to the PSNI asking for full disclosure of relevant evidence about the case.
In a statement, Asst Ch Con Singleton said: "The police service has deep and sincere sympathy with the Donohoe family for the unimaginable pain of their loss.
"I accepted copies of a petition today (25 February) and assured Fiona that we remain fully committed to finding answers for the Donohoe family.
"The disappearance and death of Noah Donohoe is subject to an ongoing coronial investigation.
"The police service continue to investigate under their Police (NI) Act 2000 duty, but also provide assistance to the coroner, so it would be inappropriate to comment further at this time."