I debated doing this recently but ultimately spent a lot of money on an LTO-6 tape drive instead, just due to the cost efficiency over time for larger amounts of data. I justified it to myself as I needed to either expand my NAS or clear stuff off it, and the drive was the same price as buying two new HDDs to expand the NAS thanks to the obscene price inflation at the moment. As I’d likely need to further expand my NAS next year (I’m shooting a lot of photo and video) I think this works out a much more cost effective way of storing this data long term when I likely don’t need to access it much.