You can do get around the nginx Plus requirement by using a module like ngx_mruby to customize the backend selection. I haven't measured the latency, so it may not be suitable for your 10ms example.

Here's a post I wrote on that ~4 years ago that uses an in-process cache [1]. It'd be fairly easy to add an endpoint to update it and pull data from Consul. I agree with you, it's a missed opportunity - there are alternatives, but being able to rely on a battletested server like nginx makes a difference.

[1] http://hokstadconsulting.com/nginx/mruby-virtualhosts