Bridgeport is signing some players, many are not New York Islander players or drafted prospects.
One-way NHL contracts (full salary) or two way NHL contracts (one salary in NHL/one in minors) are NHL contracts. Bridgeport/Worcester only signings are not NHL signings, and would require a New York Islanders contract to become an NHL player. Players 25/younger are listed on the prospect site here who have New York contracts. AHL-ECHL only players can sign with an NHL team at any time.
Justin Gill was drafted in 2023, the NYI own his NHL rights, but he signed an AHL contract only with Bridgeport. Next summer he must have an NHL contract or his NHL rights status would change to UFA.