The largest ecosystems that are deployed as production hardware right now, sure. That's because designing a high performance core takes several years, and then

The largest ecosystems that are deployed as production hardware right now, sure. That's because designing a high performance core takes several years, and then getting it into a chip, tested, into mass production, and in to computers in stores or data centres takes another three or four years. RISC-V has only existed as a frozen (ratified) base ISA for four years and a couple of months, and a lot of extra stuff that you want in applications processors for phones or PCs was ratified in November 2021, less than two years ago. You're not going to see a lot of products with the late 2021 stuff until 2025 or 2026. In terms of people starting projects now, or recently, that is indeed mostly RISC-V.