Get NFT's for account at fixed block_number

I need to take a snapshot of the NFT’s an account did own at a fixed block number. With the NFT API it seem I can only get the NFT’s that an account owns for the current / last block.
It looks like it should be possible to reverse engineer the NFT’s owned at a specific block by taking the current NFT’s and then analyzing the transfers and their block numbers.
But I wanted to check if there is a simpler solution that I might not be aware off??

I don’t know an easy solution now

ok thanks for letting me know