Here's how to enter a 1099-INT into TurboTax Online:
Under "Let's import", choose "Enter a different way."
Choose Interest, continue
Choose "Type it in myself"
Enter FEIN from payer, payer's name, and amount of interest. Choose recipient's name from dropdown box.
Also note that the interest is reportable in the year it was received- so if you amended a return for a prior year in 2025, the interest is not reportable until you file your 2025 return.