Despite the misleading name, apparently rust-vmm/vm-memory can do memory mapped I/O on a wider scope. I.e. it could be used in a project having nothing to do with virtualization. In Enarx the situation is two-folded:

• SGX needs device memory maps
• KVM based confidential computing needs whatever the name of “the thing” providing private memory areas is ATM through KVM shenanigans ;-) Have to check.