Q: What happens if I make biscotti recipe in a loaf pan? Is it a not-so sugary cake?
This would be harder/firmer than a cake.
If you bake a thin enough layer of dough (about 1/2 to 3/4" high), take it out and slice, then replace in pan and bake again (this may take a few batches), you will get cookies even from a loaf pan.
If you bake a whole recipe of biscotti that makes, say, one or two dozen cookies, all at once in a loaf pan, you will get a very dense thing, somewhere between cake & cookies.
If you don't have a sheet pan, but do want to make the cookies, you could also do them in a muffin tin. They won't have trad shape, but will taste good & be crunchy.