Very little information about this. Can’t even tell if it is going to be 32-bit or 64-bit.

There have been open source cores for running on FPGAs available for some time. Most work seem to have been for 64-bit, so this seems likely.

A “capability” (in this context) is a pointer with bounds and access rights built in. Memory tagging in hardware makes capabilities unforgeable. Cheri/RISC-V allows for multiple models: Full, hybrid and legacy. In the full model, capabilities and Cheri instructions are used instead of pointers and normal instructions — and buffer overflows are impossible. In hybrid models, capabilities are used to protect certain resources, or used for compartmentalisation within a program (cap inside legacy, or legacy inside cap). The downside is that a stored capability is twice as large as a normal pointer. 128 bits on 64-bit systems and 64 bits on 32-bit systems … despite bounds being “compressed” using a floating-point like encoding to have larger granularity the larger they are.

The CPU is a 4-core THead C910. RV64GCV. I’m longing for when there are machines that support the RVA23 profile.

Huh? I've always used a 3mm drill for a hole for M3 bolts, 4mm drill for a hole for M4 etc.

If you want a bolt to stick in a hole, you'd need to make it threaded using a tap. These holes need to be drilled even smaller (and there are charts for that), and the material would also need to be sufficiently thick or the thread will risk ripping.

I'd suggest that you instead use either threaded spacers with bolts from the top and bottom, or "barrel T nuts" if you can find them in a size that would work. There are also "Chicago screws" but they are really for leather-making so they are often not always made with as high tolerances as machine bolts.

I get only an empty page when I click the Nickel link.