Новая грамматическая тема: местоимения с частицей «угодно» — «кто угодно», «что угодно», «где угодно», «когда угодно», «какой угодно», «сколько угодно».

In this pattern, угодно is a fixed particle that turns a question word into a free-choice word.

It adds the idea of no restriction:

• кто угодно = anyone at all
• что угодно = anything at all
• где угодно = anywhere
• когда угодно = anytime / whenever
• какой угодно = any kind of
• сколько угодно = any amount / as much or as many as you want

So the word is no longer asking a question. Кто? asks who?, but кто угодно means anyone.

Yes, in English-style grammar they are closer to adverbs of place and time.

In Russian grammar, words like где, когда, куда are often grouped with pronoun-like words because they point to place, time, direction, etc., rather than naming something directly. You may see terms like pronominal adverbs.

For learning purposes, the important thing is this:

• the same pattern works with кто, что, где, когда, какой, сколько
• all of them can combine with угодно to express free choice

So even if the labels differ, the grammar pattern is the same.