The advancement "Isn't It Scute?" can be obtained without getting a scute from a leashed armadillo.

When you use a brush on an Armadillo with a lead, you get the advancement "Isn't It Scute?" although no scute is dropped.

Video proof:
https://1drv.ms/v/c/707fd0e5f23ae98d/ERTkeYg9GrlIr-cYvAQ1YBoBzNpkFE0Mqkv9tbCLlgY2Zg?e=cxzXe4