@ascherbaum having built some high density RPI cluster servers.
I'd go with CM4s over stock RPIs.
I will say, cabling is very easy to underestimate.
Even with on PCB switches, and in chassis switches, getting 96 nodes into 2U is a struggle. Especially if you want decent storage too.
@intrbiz For practical purposes I agree with you.
The discussion in Prague centered around Raspberry Pi, so I tried to stick with that.