Verifying ownership of utxos Is there any other way besides signing a transaction to verify ownership of utxos?
To 'own some bitcoins' is to own the private key that allows a UTXO to be spent, so your question can be refined to "how do you verify ownership of a private key that controls a UTXO?"

There are a few ways you could do this:


Sign a generic message with the key, such as "I am the owner of bitcoin address 1a5Ag23...."
Sign a transaction with the key, spending the coins to a new address (you could post the address prior to broadcasting the tx, to prove the coins are not just moving by coincidence)
You could show off the private key itself (but this is a very bad idea! The bitcoins probably would not remain yours for long...)