Adding SSD drive to iMac

I have an iMac 27” 2017. I opted for 1TB SSD. I am assuming this is a blade drive on the back of the logic board. Am I right? If so, this would mean I could potentially add a second SDD, which I would install in the place where regular spinning drives are put in the fusion configuration, right?

If so, is the SATA connector cable already there waiting to be used, or would I have install one (what about the thermal sensor ???) and plug it in the SATA port on the board somewhere???

Nothing under PCI.

Under SATA/SATA Express:

Intel 10 Series Chipset:

Vendor: Intel

Product: 10 Series Chipset

Link Speed: 6 Gigabit

Description: AHCI Version 1.31 Suppo

... and under Storage:

Macintosh HD:

Available: 515.54 GB (515,539,804,160 bytes)

Capacity: 1 TB (1,000,240,963,584 bytes)

Mount Point: /

File System: APFS

Writable: Yes

Ignore Ownership: No

BSD Name: disk1s1

Volume UUID: 7E42863E-7593-36FC-8695-2D4F3E3A3085

Physical Drive:

Device Name: APPLE SSD SM1024L

Media Name: AppleAPFSMedia

Medium Type: SSD

Protocol: PCI-Express

Internal: Yes

Partition Map Type: Unknown