I've got a downstream customer asking for help;  they have a private internal network that I've taken to calling the "partial-mesh network from hell": it's got two partially-overlapping radio networks, mixed with islands of isolated fiber connectivity.

Dynamic routing protocols (IS-IS, OSPF, EIGRP, etc.) generally will only select the _best_ path, they won't spread the load unless all paths are equal - and they are very unequal in this network, ECMP would likely fail horribly.

The network is becoming bandwidth-limited, so they're wanting to make use of all available paths, not just the single "best" path.  It's also remote and spread out, so adding new links or upgrading existing links is difficult and expensive.

Oh, and their routers are overdue for a refresh, so acquiring replacement h/w is now possible.

Has anyone come across any product or technology that can handle the multi-path-ness and the private-network-ness like a regular router, but also provides the intelligent per-flow path steering based on e.g. latency, like an SD-WAN device (and/or some firewalls)?