Jonathan Mayo reports that the Pirates gave Connor Joe a bonus of $1.25 million, about $208,000 below his bonus pool figure. They also saved about $40,000 on seventh-rounder Nelson Jorge and $24,000 on third-rounder Jordan Luplow. Ninth-rounder Kevin Krause signed for his full pool allotment of $143,600.
That means all the bonus pool figures are in, and (following from the Pirates Prospects article linked above) the Pirates have spent $131,300 less than their bonus pool of $7,063,700, assuming they haven't already spent any of that money on later-round picks signed for over $100,000. The Pirates can also go slightly over their pool without losing a top draft pick next season, although they would have to pay a tax. That gives them about $477,000 to play with for late-round signings like 11th-rounder Gage Hinsz. The rules permit teams to spend $100,000 on each late-round pick without it counting against their bonus pool, so the Bucs could spend up to about $577,000 for Hinsz or another late-rounder.
This article makes it sound like Hinsz has some sort of agreement with the Pirates for more than $886,800, but that now seems extremely unlikely, because the Pirates aren't going to give up next year's first-rounder to sign him. It sounds like Hinsz may have been a backup plan in case the Bucs couldn't sign Mitch Keller or Trey Supak, both of whom signed for more than their allotments. So I wouldn't count on the Pirates signing Hinsz. There are a number of other players from the late rounds who remain unsigned, however.