MTG: Arena. Is there any way to use packs other than open them?
No, there is currently nothing that can be done with packs besides opening them and claiming the cards. 

The only modifier to opening packs is that opening fifth copies of a common or uncommon card contributes to your vault. The vault is a hidden percentage that, once you reach 100%, awards you 1 mythic wild card, 2 rare wild cards, and 3 uncommon wild cards. Also, I believe that if you have every rare and/or mythic in the set, the rare and/or mythic spot will be replaced by gems.