I’m not extremely familiar with PANCOM, but it's not something you would program as a trunked system with talkgroups.
PANCOM stands for the Panhandle Regional Interoperable Communication System. It was built through the Panhandle Regional Planning Commission, which is basically the regional council of governments style organization for the panhandle.
PANCOM is a VHF based interoperability system using P25. You can think of it more like a network of conventional VHF repeater channels spread across the Panhandle, not DMR nor a P25 Phase II trunked system.
So for your Whistler, you would want to program the actual PANCOM VHF repeater frequencies as conventional channels, not as a trunked system.
The easiest way to think about it:
PANCOM = regional VHF repeater/interoperability system
not DMR/trunked etc
no talkgroups
program the individual frequencies conventionally
A local example from my area would be the North Central Texas Council of Governments system. NCTCOG helped coordinate regional interoperability communications in the Dallas/Fort Worth area, but their setup was more of a 700/800 MHz P25 trunked overlay/interoperability system. PANCOM is the Panhandle version of regional interoperability, just using a more straightforward VHF conventional repeater setup.
The goal is the same...give public safety users across the region common channels they can use without having to figure out what local mutual aid channel, NIFOG channel, or county specific repeater is available in every area.
I attached an older PANCOM map. The map I found is dated 2010 and was retrieved around 2018, so it may not be completely current. At the bottom, it shows that some sites were linked by VHF, others by microwave, ethernet, etc.
Look for the PANCOM frequencies listed for your county or nearby counties in RR and program them as conventional VHF channels.
EDIT: It appears some counties use them as full time dispatch channels, so you'll probably hear a lot more routine traffic than interop if that's the case, where as in Potter County it looks like they use their own trunked system, not sure if it's patched to the PANCOM VHF channels or not. Something to keep in mind if you don't hear traffic in some areas.