Meanwhile, defender Finn Jeltsch has played down speculation linking him with a route in the opposite direction.
"We still have three weeks. There's also interest from a number of clubs. There's hard bargaining going on. But I'm confident that we'll see some movement," Hainer told Abendzeitung when asked about the trio.
Palhinha, 31, is currently the subject of a two-way chase between Newcastle United and Aston Villa, with the Portugal international having spent last season on loan at Tottenham.
Zaragoza has recently been linked with Deportivo Alaves, Sevilla, Espanyol and clubs in Saudi Arabia, while no concrete destination has yet emerged publicly for Boey, who has struggled to hold down a regular starting spot at right-back since his move from Galatasaray. None of the three are considered part of head coach Vincent Kompany's plans for the new season.
Meanwhile, VfB Stuttgart centre-back Finn Jeltsch has shown no ambition to force through a move to Bayern Munich anytime soon, despite persistent reports linking the 20-year-old with a switch to the Bavarian giants.
"I've read that too. But it's not something I'm really thinking about. My full focus is on the upcoming season with VfB. I have an ideal environment here and I can play Champions League football," Jeltsch told Stuttgarter Zeitung.
Jeltsch is also on the radar for a first senior Germany call-up, and made clear that representing his country remains a driving ambition.
"Definitely, that's clearly my goal. Playing for Germany was already something absolutely special at youth international level. And if Jurgen Klopp gets in touch, I'd be delighted," he said, referencing the newly appointed national team coach.
Jeltsch joined Stuttgart from 1. FC Nurnberg in February 2025 for around €12m and has since established himself as a regular starter, with his market value now estimated at upwards of €35m.