Haven't seen the proposal yet, but didn't search in general. But the summary says Chris wants even tougher gun laws and banning evil guns. That seems to be a pattern in the East (and including CO). The article discusses that Chris would have national problems with his stance if he ran as a GOP candidate.
The same would go for Gov. Cuomo - sure he would be a Democrat but would be reviled on his gun stance by much of the country.
Now I'm not trying to do a political rant (against our rules) but it seems to me (and research shows) that the operative issue is not party on gun issues but basically urban vs. rural and Eastern vs. the rest of the US. Eastern seems to mean an axis of NY, CT, MA, RI and NJ. Maine, VT, and NH seem ok - unless they get a demographic hit. CO gets driven by urban - Boulder and Denver. Same with IL and Chicago.
I think we will a strong state polarization in gun laws and party won't make that much difference. Plenty of 'conservative' city or suburb types that are strongly anti. Peter King, from NY, or the vile Joe Scarborough (praised by Biden) come to mind.