Hello hoping to get a solid answer here as I am seeing conflicting information online. We are moving to a new NS instance from our existing one and need to take closed FY24 transactions to the new instance (invoices, vendor bills, vendor credits, credit memos), what is the best way to do this? I am thinking flat file is best as COA is remaining the same.

CSV import or the Celigo tool most likely. In general I'd recommend against bringing detailed info into a new instance though. Especially if there are multicurrency impacts. It's a headache.