Other candidates for her hand were: Bogusław IX, duke of Stolp in Pomerania (supported by emperor Sigismund and Eric of Pomerania) and son of king Janus of Cyprus (not sure which one). However, Cyprus was far away, so I believe king Władysław II would have chosen someone closer to home.
Personally I would have chosen Bogusław, which would improve Polish relations with HRE, give Poland a foothold on the sea coast, with good chances of cutting of the Teutonic Order from reinforcemens from the west in case of another war.
As far as Hedwig's claims to Polish throne goes, they were more or less irrelevenat, since king Władysław II had also 2 son, Władysław and Kazimierz. Władysław III was 10 when his father died, so IMO at best Hedwig's husband might push for regency. That would be interesting - Bogusław might be acceptable candidate fot Polish lords, but I think Zbigniew of Oleśnicy would have won as he did IOTL as the leader of the Regent Council.
Had Hedwig married Frederick II, I do not believe Polish lords would have accepted him as a regent: he was more or less an independent ruler and his country's interests might possibly be in conflict with Polish interests.