Is 'btrfs' used only for 'btrbk'?
Does it prevent data loss due to SSD failure, or just user errors?
What are the recommended data storage file systems nowadays?
What are the recommended data storage file systems nowadays?
In this setup with a single SSD, it has no role in preventing data loss if the SSD itself fails, but it should prevent data loss in case of user error.
If possible, use ZFS, and in case that isn't an option, use BTRFS if you need the data integrity guarantees and at least some protection against faulty hardware in mirror/RAID-like scenarios. That's my two cents.
Benefits in this context would include checksumming, compression, snapshot + incremental send, built-in kernel support (which is why I use it as root filesystem even on machines that use ZFS for data integrity), very flexible RAID1 setups, the option for DUP data on an SDcard (still unclear to me if this would improve odds of recovery in case or error or just increase the odds of corruption in the first place).
ZFS may be king in many / most scenerios, but I've been very happy with my Pi on BTRFS root that I've used with Ubuntu server, Raspbian, and now NixOS[0], on Pi 2/3/4.