Nottingham Forest have become the latest club to join the chase for Noonan, with interest set to intensify as the 17-year-old approaches his 18th birthday.
Noonan turns 18 on 31 July, the age at which, post-Brexit, players from the Republic of Ireland can move to clubs in the UK without requiring a work permit.
He already has a long list of admirers, including Chelsea, Manchester City, Celtic, Ajax and Hoffenheim, the latter said to have agreed a £1.5m fee with Rovers earlier this year before Noonan opted to stay put.
The Irish Examiner reports that British clubs have been prepared to wait for the post-Brexit threshold, but will now face fresh competition from Forest, where former Republic of Ireland midfielder Andy Reid works as a coach.
Rovers are in no rush to sell as they prepare for a Champions League campaign, with matches against Maltese champions Floriana scheduled for 7 and 14 July.
Noonan came through the academy at St Patrick's Athletic before joining Rovers last year.
Manager Stephen Bradley praised the teenager's attitude as much as his ability.
"Michael is one of the best young players in the country. He can do a bit of everything," Bradley said.
"His standout attitude for one so young is his mentality. His mentality is strong and a desire to get better and push on.
"As a young player, that's a really important attribute to have. He wants to work hard, he's dedicated to his craft and has real ambition to be a top player."
The growing list of suitors reflects the scale of interest in one of Irish football's most highly-rated emerging talents, with Forest's involvement adding a Premier League dimension to a chase that has so far been dominated by clubs from elsewhere in England and continental Europe.
Rovers' Champions League involvement this summer gives the club genuine leverage in any negotiation, with Noonan's continued progress at a club playing continental football likely to only strengthen his market value as his 18th birthday, and the accompanying eligibility for a UK move, draws closer.