oh, you are new to HN, because you would not need to ask such question if you were reading HN in the last few years...

You can start on risc-v wikipedia page and/or on the official risc-v web site.

I would say they’re smart to invest in ARM over RISC-V for the time being. It was hard enough to get the industry to support x86 and ARM64. I mean the Windows transition is still not fully complete, and they’ve been trying since Windows 8.