It would be awesome as well if we could patch this on clientUrl of mikro orm for root method.

I was just looking closer into this, and apparently pg doesn't support multi-host URLs on its own, you need pg-native and nativeConnectionString option instead based on brianc/node-postgres#1470 (comment).

Is it something we plan to support on upcoming versions? Either natively or with external deps

Yeah, I can take a look at that in v7. I guess it could be already hacked via driverOptions now, you can even pass a configured knex instance there:

Cool. Then maybe I will start with that and once v7 is out I can swap.