The dev machines I built for the office all have gen 4 NVME drives (sabrent or gigabyte-aorus) in them and I do not use the heatsinks that come with the drives. I use thermal pads in combination with each motherboards cooling setup. These large heatsinks (in my exp) are not necessary for the Gen 4 drives. I do NOT have a SabrentR+ or the new Samsung drive yet, but I do not expect them (thermally) to be any different given the speeds the new drives are showing compared to what is available currently (Aorus, Sabrent ,etc).
I do not know this for sure, but I would expect there to be a metal heatsink with thermal pad cover over the expansion bay in the PS5 all most all pcb manufactures are including these with mobo's now.