Fluorescent dyes for staining cellular membranes are discussed here:

https://www.thermofisher.com/us/en/home/life-science/cell-analysis/cell-tracing-tracking-and-morphology/neuronal-tracing/cell-membrane-staining.html

I used successfully cytoplasmic membrane staining kits of PromoKine  for chloroplast and thylakoid membrane, so for nuclear membrane. I sugest for nuclear membrane  FM4-64 dye. FM4-64 in the nuclear envelope  may detect a difference in the composition of negatively charged lipids between the outer and the inner nuclear

membranes,