Donaghy fronted an impromptu press conference at Broncos headquarters on Monday, and again admitted the club erred in the handling of Adam Reynolds' farewell.
He also insisted he wants under-fire coach Michael Maguire to stay on at Brisbane, and backed his staff to turn the club around after a horror NRL title defence.
But the Broncos chief executive was most expansive in his comments around Haas, who shocked Brisbane and the NRL by signing with Souths for three years in February.
"The door's always open to Payne," Donaghy said, ahead of Thursday's final-round clash with Canterbury.
"He's been a wonderful, magnificent servant for the football club for a long period of time.
"He's won six Paul Morgan medals. As Madge (Maguire) said, I think at some point he'll probably come down as an immortal.
"He's been an amazing contributor to our football club, hopefully one day we might see him back in Broncos colours."
If Haas ever becomes a free agent at Souths, he will likely attract significant interest with the PNG Chiefs among those to try and approach him this year.
Asked about the prospect of one day returning to the Broncos, Haas would not be drawn into the conversation.
"I can't tell the future, I'm just trying to be present," the front-rower responded.
Haas did not want to go over old ground on his reasons for leaving Brisbane, and said he had not spoken with the Broncos for their wide-ranging review.
The prop also said he did not yet know if hand surgery would stop him playing for Samoa in the upcoming World Cup, but hoped he could assist the team regardless.
The 26-year-old labelled a round-one win over North Queensland in 2020 and last year's grand final success as his two biggest Broncos highlights.
"Obviously this club is a very special club and we get looked after, but I think more the connection with the boys (I'll miss)," Haas said.
"I remember coming in a bit raw and got in a bit of trouble the first few years of my career.
"If it wasn't for the Broncos, I wouldn't been the man and especially the footy player I am."
Brisbane's horror season was encapsulated in the Reynolds debacle last week, with mixed messaging over the retirement-bound skipper's fitness and ability to play the final two rounds.
Vision of a lap of honour at Suncorp Stadium last Thursday night was cut off to go to a sponsor activation, after a 45-minute big-screen outage.
Donaghy took a thinly-veiled swipe at the stadium for the matter on Monday, but also conceded the club should have prioritised the departing players.
The nightmare end to 2026, which included two wins from the past 15 games, has piled pressure on Maguire as coach.
But while Donaghy insisted Maguire and his staff would be well prepared for the pre-season, he would not make comment on when the two-time premiership-winning coach would be extended beyond next year.
"We'll have those discussions behind closed doors," Donaghy said.
I've always said I'd love for Madge to be our long-term coach.Â
"But with respect to people's HR confidentiality, I think we'll keep those between Madge and I."
