>RISCV isn't that standardized that there won't be a plethora and mess of peripherals available from every manufacturer. It will be much like ARM.
Hardware, sure. Although not as much, as standarization goes further than ARM, with the platform profiles including e.g. standard serial ports, interrupt controllers and so on.
In practice, on the software side, it'll be closer to your usual IBM PC clone.
The boot process, with SBI and UEFI standarized, is also part of the relevant platform profiles. How to get to the point where a kernel loaded in memory is defined. The environment this kernel finds is also defined. The kernel does actually get a description of the hardware.
ARM did very little of that, and did it too late. RISC-V has it all in place before the hardware is even there, so it should be alright.