Lucca, 25, joined Forest on a temporary basis from Napoli in January after spending a difficult first half of the campaign at the Neapolitan club.
He scored once on his Premier League debut — against Leeds United — but has since been largely absent from head coach Vitor Pereira's plans. He was not selected for any league match between February and late April, and was not called up to the squad at all during that stretch. He returned to the bench for Monday's 3-1 win at Stamford Bridge but did not play.
His Europa League involvement has been more consistent. He started against Fenerbahçe and Midtjylland and came on as a substitute in the return fixtures, but was an unused substitute in the quarter-final against Porto and the semi-final first leg against Aston Villa.
Lucca was one of three strikers Napoli signed last summer as they sought cover for Rasmus Hojlund, but a combination of limited opportunity and inconsistency in front of goal left him without a route into the team. Napoli paid Udinese approximately €10 million to make him permanent in January before immediately loaning him to Forest, suggesting the club believe in his potential — but not necessarily in a role for him at the Maradona Stadium.
Fiorentina's interest is tied to Moise Kean's future. If the Italy international activates interest from a major club — his release clause stands at €62 million — Viola would need a like-for-like replacement in the centre-forward position. Lucca, contracted to Napoli until 2030 with a carrying value of €35 million on the books, would not come cheaply even on loan terms.
Nottingham Forest face Villa in the Europa League semi-final second leg at Villa Park on Thursday, needing to protect a 1-0 lead from the first leg at the City Ground.