Raid/NAS, as many others have said, isn’t a backup.

However, you could have a single NAS and backup to AWS Glacier where storage costs for larger files is cheap going in and getting out in DR scenario is expensive, but maybe covered by your insurance depending on the DR event.

I’ve used 7digital and hdtracks.

Word of caution on 7digital; I’ve found that sometimes they’ll lose the licence for the files so my downloads will no longer be accessible. Always download immediately and backup.

Also found one file on a NIN album corrupt.

Having setup my own DIY I found that great for me, as I knew how it worked and had a lot of fun learning. When I needed an off site backup that worked out the box and was low maintenance I went with Synology