That is a great point - PCIe 3.x access for those drives will be fast, just not (quite) as fast as PCIe 4.x - but that also translates into lower temps overall, unless you're crunching away at data, gaming, etc. - basically any drive intensive activities.
My motherboard has integrated heatsinks for the 3x NVMe M.2 slots, so my temps are 39, 42-43 and 49 for the 3 drives, with the 49 drive being directly under the GPU. The last couple of times I cleanly installed Windows 11 I paid attention to which drive was the hottest and relegated that for storage only, so it would be used the least, and the coolest drive is my system drive, so knowing the temps based upon location, especially if one runs significantly cooler than the other(s) helps in planning how to install your OS as well.
Being a desktop, with gobs of air cooling in dual push/pull configuration, I don't think I've seen any of my drive break 58 to date. With laptops, while a heatsink may help, the best thing you can do is to keep hte air cooling vents free and clear of debris and dust - on a regular basis, no less. If you can find heatsinks that actually fit in your chassis, it won't hurt to have them - but I don't see that they will be required, more like recommended.
