Asus is already offering public beta BIOS versions supporting the Resizable BAR feature on most of its Intel Z490, H470 and B460 motherboards, while the BIOS versions supporting AMD's SAM for older X470 and B450 models is still restricted to private testers.
https://www.notebookcheck.net/Asus-implements-Resizable-BAR-aka-AMD-SAM-support-on-Intel-Z490-H470-and-B460-motherboards.506887.0.html