NV claims you need RTX gpus to be able to fully use DLSS2.0 to its full extend. They say tensor hardware assists in the process. That means the hardware features help out. If they lie or not that isnt the topic for it.
The thing is, AMD hasnt shown anything so far that matches dlss (with RDNA2). Its the same story with RT before RDNA2 made its debut here on the forums, as the one your having now with DLSS. Its very realistic to assume that RDNA2 wont compete on the same level as DLSS2.0 on RTX gpus does.
I feel its the same as the RT discussion/tech, it will be there on RDNA2 (and any other gpu out there) but less performant/capable. AMD might introduce some form of improved acceleration in RDNA3+ gpus, same goes for ray tracing, their next iteration is going to be much better.
Like said it wont matter all that much since well, no one is able to get any of the current gpus anyways. We will see how rdna3 stacks up against the competition, it will be their 2nd gen rt and reconstruction tech going on so its intresting to say the least (and the 100TF leak).
More often then not, a solution that fits all gpus (even between different ihvs) is most likely not going to be as capable as a solution for specialized hardware variant.