I had a commodity ETF at one point, and it sent me a Schedule K-1 like a partnership. This requires a little more work because you have to map the boxes on the Schedule K-1 to the various parts of your personal return, and, in my experience, standard commercial tax software (specifically TurboTax and HR Block) have spotty support for this. It will depend in part on the ETF and what the ETF held / did during the year.
It is a bit easier a retirement account because then you don't generally need to file a return on the income and these problems "mostly" go away. In theory, if the ETF derives income from things like loans, you could have to file a return on your retirement account that you otherwise would not have had to file, but you probably won't hit this case. It would trigger if you had excess "unrelated business income" (UBI) - Last I saw the threshold was $1000, which you probably won't get. Even in a tax-advantaged account like an IRA, UBI is taxable above the threshold.