Look at the heat sinks on gen 5 SSDs. To me the marginal speed benefit of the platform introduces a lot of problems you have to deal with like heat. I would’ve preferred they just focus on bandwidth to allow users to get the same performance as Gen 4 with half the PCI lanes.
Along the same lines as the Transcend card is Blue SCSI which is a little raspberry pi based SSD for vintage Macs that lets you FTP into the drive from a modern machine for file transfer.