I guess my question is could this be used as a ISP core router running CGNAT?
i think its a bad idea, why?:
because CG-NAT will be done by Software using CPU on Fast_track mode with many connections tracked beyond what 2
216 can do with hardware offload
i think 2
216 is suited for a specific role as core or border router running with hardware offload at full wire-speed
for CPU related tasks 2
116 is a better choice because it has the same CPU as 2
216 and cost a fraction,
i think the 4x 10g interfaces included on 2
116 are more than enough to saturate it in CG-NAT role i think maybe 20 to 30gbps will be the ceiling in that role for 2
116 / 2
216
there is an exception: if you are aware of this and want to opt for 2
216 to reduce your space and power usage getting the CPU muscle and 100g/25g switch in a single machine, that can be a good use case