Comic Strips

It's unlikely that insects (or any animals for that matter) are a better use of the land, because ultimately animals need to eat plants, too, and they use up a good chunk of the energy themselves.

Occasionally, you can grow grass where proper crops won't and animals can graze there, but to my knowledge, this isn't particularly relevant in practice, because farmers will typically feed more nutrious food to minimize the time until the animals can be slaughtered.

You talk about complete protein, by which I assume you mean the amino acid distribution, but I find it hard to believe that the inefficient land use of animals is offset by them converting some of the amino acids to be better suitable for us.
Because ultimately, if you manage to grow more lentils and whatnot, you can totally just eat more lentils to reach your 100% of each amino acid.
Wealthy cultures eat significantly more protein than is actually needed, for example.

Veganism seeks to exclude animal exploitation and cruelty as far as is possible and practicable.

For a Western audience, where one would have access to a well stocked supermarket, that would generally mean a complete boycott, but it does ultimately come down to the individual to decide what is and isn't practicable. If you have nessary medication that contains animal products, or is tested on animals, for example, I don't think you'd find anyone expecting you to give that up.

As for insects, they're within the kingdom of Animalia, so yes, veganism applies to them too. That said, you can't go through life without ever stepping on an ant, and I don't know anyone who'd place the exact same value on an fly and a cow. One has a vastly more sophisticated brain and nervous system. That said, I generally don't try to play "utilitarian calculus".

Ultimately it's a "do your best" situation.