They do infrequently utilize the old conventional frequencies direct to speak unit-unit without Trenton listening. You'd need to be in the area though since I'm pretty sure they're on low power from what one of their officers told me last year.
I noticed in the past few days, the NJ Parks Police talkgroups have not been simulcasted on the NJSP 800 TRS at all. So I'm going to say it's safe to assume at this point that the DEP talkgroups on the NJSP 800 side are no longer active. They are still active in Phase 1 mode on the NJICS 700 side at all times currently.
I had heard that 800 MHz smart zone system was going to be phased out by the end of 2022. This came from a close source to the system which doesn't necessarily mean it couldn't be delayed till later.