We do, and it works well.

We put all RFCs in a dedicated single repository. The initial submission of an RFC is a merge request. The review and approval process is similar to that of a code MR. The same happens to subsequent updates to the RFC.

RFCs are versioned internally. But, since we're pretty small, most are still 1.0.

Our team is only under 10, so I haven't thought about the details of scaling this up to larger or multi-team environments. However, I don't think it'd have issues scaling as long as ownership and vision are clearly defined.