I Own Single Drive white WD MyCloud. Right now it has a permanent yellow light and inaccessible via local web and (at least from my mac) directly via Ethernet cable. At this point, after multiple attempts to reboot, etc, I am willing to give up and buy another NAS (one with double open bays, at least).
BUT I still want to get my data back, hence this question: If I buy something like Sinonlogy NAS with an open bay, will I be able to unscrew the drive from this WD, insert it into Sinology, Insert another drive, and mirror them (assuming drive itself is working, of course)? Or it will save me time and worry if I go to a local data retrieval service, instead?
No. Other NAS manufacturers use different firmware and hard drive structures/layouts/formats.
If you want to retrieve your data you can remove the My Cloud hard drive from it’s enclosure and attach it to a computer running either Linux or a third party Linux driver. One can use a USB to SATA adapter, docking station or spare SATA port on their computer. One can use a Linux boot disk/USB flash drive or third party Linux drivers like that form Paragon Software (https://www.paragon-software.com/home/linuxfs-windows/).