Any UTXO can be used as input for a transaction. The thing with dust UTXO is that they cannot be spent without other inputs increasing the value of the sats being spent to compensate for the dust. Vires in Numeris.

What I don't know is if a miner is able to include a transaction that only spends from a single dust UTXO since transactions built by miners don't suffer from relay/mempool related restrictions (like zero fee transactions).