[Enhancement]: Consider if we should restrict secure mode to x86-64 only, as substrate does

[Harrm]

Description

The relevant discussion in rust polkadot sdk:
paritytech/polkadot-sdk#2321 (comment)

Motivation

Malicious PVFs may be able to detect the platform they're running at and do their malicious stuff.

Additional context

No response

Are you planning to do it yourself in a pull request ?

Yes