In applications processors chips about to come out in the next 12 months, such as this XiangShan and the SG2380, are getting up into the performance level of 10 year old Zen and Core i5 etc, which is still a perfectly fine performance level for many people and uses.
Linux has been available for RISC-V for many years, a number of distros have 2nd tier support for RISC-V, probably moving to 1st tier soon.
Android is working towards 1st class support for RISC-V, with the desired ISA extensions, fast enough hardware, and full software porting looking to converge into competitive products around 2026-2027.
Arm is NOT a "common ISA". It is proprietary and support can be arbitrarily removed at any time. Since 2023, Arm's highest performance CPU cores have dropped support for the 32 bit ISA(s) even for user programs. That's orphaning an almost 40 year history of 32 bit Arm software, restricting it to being used only on legacy CPUs which will rapidly have much less performance than newer high end CPUs.
At the same time, the low end Arm microcontroller family remains 32 bit only. And the 32 bit and 64 bit ISAs are totally different to each other.
RISC-V vendors on the other hand are happy to license you a 64 bit core with Cortex-M0 or Cortex-M3 size and features. These are often valuable as a control processor in a bigger chip with 64 bit applications processors and >32 bit address space.
In RISC-V the 32 bit and 64 bit ISAs are almost identical and it's very cheap and easy to support 32 bit code on a 64 bit CPU -- the RISC-V spec fully supports this, though demand is low as there is not yet a lot of legacy 32 bit RISC-V code. Most current RISC-V CPU cores don't support this, though for example the THead C908 does.
It's probably 20-30 billion by now.
And actually no one really knows the total because no one is required to report that they are using RISC-V, let alone sales or production numbers.
It comes down to adding up those companies that have said. WD/Sandisk are shipping several billion a year, and started early (even before the formal spec). Samsung said in 2019 that the Galaxy S20 had two RISC-V cores in every phone. They are now publicly known to be porting their Tizen OS and the DotNet language execution environment to RISC-V, for use in TVs and "other unspecified products". They ship quite a lot of stuff. LG are also known to be switching to RISC-V. Qualcomm have a handful of headline Arm applications processors in chips such as the Snapdragon series, and possibly a dozen or more unannounced RISC-V CPUs in the same chips.
But "displacement" does not mean installed base of CPUs or even current sales of CPUs in existing products. It is not even about new products that use existing chips.
"Displacement" means the proportion of new chip design wins, which over the long term feed through to the above measures.
Both Andes and SiFive have probably individually (and certainly combined) for several years now had more new design wins for CPUs in new chips than Arm.
There are an increasing number of formerly skeptical manufacturers putting both an Arm core and a RISC-V core in the same chip, the most well-known example recently being Raspberry Pi, a company that is simply full of ex-Arm and Arm-centric Broadcom employees.
The 10b+ cores by December 2022 were fabricated and deployed physical cores inside physical chips, brucehoult was responding to your non-sourced "There are 100 billion embedded ARM processors in operation" statement.
Of course this number is much larger now, as RISC-V adoption has exploded. RISC-V is not a fad that will go away overnight. It has long entrenched itself very deeply in this industry.