Adding a dust UTXO along with a larger UTXO as inputs to a tx does not magically remove the dust, or make the dust any more economical to spend.

A P2PKH tx is about 546 bytes, meaning you would have to pay at least 546 sats to spend it. Segwit and Taproot txns are a bit smaller ~450 bytes.

Suppose you have a 294 sat utxo and a 5000 sat utxo in the same wallet. You could just spend the 5000 sat UTXO for approx 500 bytes (500 sats fee at 1sat/byte or about 10% fee relative to the amount sent), or you could spend the 294 sat utxo for approx 500 bytes (about 170% fee), or you could spend both utxos for approx 1000 bytes (about 20% fee).

Every dust utxo is just a future "forced" donation to miners (if it gets spent) or a perpetual donation to all bitcoin holders (by burning or essentially removing those sats from the supply circulation).

You could try to convince someone that your sats are "rare" and trick them to pay you more then 1 sat per sat.