Makassan language of Indonesia has -aŋ 1. suffix used to form passive nouns: that on which, in which, with which something is done; 2. suffix used to form deverbal adjectives or nouns with a passive sense, and carrying an implication of possibility or desirability .
Do you think that this is connected with अङ्ग ?
If so , then maybe the गुण for vowels of ऊ अ > ओ in Makassan. It appears that this happened in Aceh , Indonesia , perhaps indicating an earlier similarity using Skt. गुण .