GamersNexus recently confirmed that NVIDIA is working on a platform-agnostic alternative to AMD's Smart Access Cache technology. According to NVIDIA, their Resizable BAR solution delivers a similar performance uplift as Smart Access Cache (up to 10 percent, depending on the title).
https://www.notebookcheck.net/NVIDIA-s-Resizable-BAR-coming-to-all-Ampere-RTX-3000-cards-soon-as-a-Smart-Access-Cache-alternative.503981.0.html