Yeah. You can pull drives out and mount them in regular Linux. Synology uses standard Linux tools.

https://kb.synology.com/DSM/tutorial/How_can_I_recover_data_...

I haven't tested it on Synology, but at least on ASUSTOR, the RAID arrays are set up using mdadm internally—so I was able to pull the drives, plug them into a Pi through a SATA card, and recover the array pretty easily using mdadm.

The vendor NASes do seem to add extra partitions besides just one main 'md0', though—so you probably couldn't expect to yank the drives from a Synology and pop them into an ASUSTOR directly.

I also tested pulling drives configured in the Drivestor and putting them in the Lockerstor, and that worked, but there were quirks if I tried in the opposite direction.

In the end, I would rather make sure I have a complete/separate backup of the NAS before attempting to move the drives, just in case.

I haven't tried pulling one of the drives from my system and trying to read it with another box but I imagine just about any Linux system should be able to read BTRFS drives, no? Under the covers Synology's DSM is Linux with some proprietary apps on top.

I'd lean toward restoring from backup either way, since the hardware failure might have caused data corruption that's not immediately obvious.