You can also use MergerFS+SnapRAID over individual BTRFS disks which will give you a pseudo-RAID5/6 that is safe. You dedicate one or more disks to hold parity, and the rest will hold data. At a specified time interval, parity will be calculated by SnapRAID and stored on the parity disk (not realtime). MergerFS will scatter your files across the data disks without using striping, and present them under one mount point. Speed will be limited to the disk that has the file. Unmitigated failure of a disk will only lose the files that were assigned to that disk, due to lack of striping. Disks can be pulled and plugged in elsewhere to access the files they are responsible for.

It’s a bit of a weird-feeling solution if you’re used to traditional RAID but it’s very flexible because you can add and remove disks and they can be any size, as long as your parity disks are the largest.