Since these kinds of things are rarely talked about and much more commonly written, there is no standard or agreed-upon pronunciation for these things. People have different ideas on how to pronounce even some of the most common constructs like
That said, when confronted with something that is unobvious to pronounce, I usually use pronunciations in my head that would be meaningless/weird/silly if said out loud. The most common ones for me are hm and ding. For example, I read
int as int ding dong. When talking to a real person, however, I’ll probably say int array.
It gets unwieldy with characters that have longish names if you need to be unambiguous when talking to someone else; for example, open curly brace (5 syllables). By comparison, backtick is a pretty snappy name. I think System dot Nullable backtick one is pretty much the shortest you’ll be able to do without being ambiguous.