I think it's a stretch to claim that proprietary software is inherently anticompetitive, though I won't argue that Nvidia as a whole is often very anticompetitive.
Implementing DLSS is no more fundamentally difficult than implementing FSR. Source-availability only makes things easier in certain edge cases, most uses will just use the precompiled library provided by the vendor. You don't need any kind of special permission or agreement with Nvidia to use DLSS. The interface for these libraries is so similar that there are already community-made wrappers that adapt between the two for games that only support one.