You mean like calamari fritti? I only tried a single bite of that once and decided it felt like battered, fried worms. My biases aside, I'd imagine the batter would be similar to what you'd use on onion rings.
I punched vegan onion rings recipe into google and got this
as my first search result, as well as a few more similar one
s. I'd try that and adjust the seasoning to include something seaweedy and possibly other things you might find in an actual calamari recipe.