I have seen multiple production systems, in multiple orgs, where "he monolith" provides somewhere in the region of 50-100 different things, has a pretty hefty footprint, and the only way to scale is to deploy more instances, then have systems in front of the array of monoliths sectioning off input to monolith-for-this-data (sharding, but on the input side, if that makes sense).

In at least SOME of these cases, the monolith would've been breakable-up into a smaller number of front-end micro-services, with a graph of micro-services behind "the thing you talk to", for a lesser total deployed footprint.

But, I suspect that it requires that "the monolith" has been growing for 10+ years, as a monolith.