Yes, we hear Splunk complaints quite often. :)

Here is a doc on using TimescaleDB as a horizontally-scalable, easy-to-deploy, operationally-mature data store for Prometheus data (i.e., metrics), put together by another of our engineering teams:

Building an open-source analytical platform for Prometheus

https://tsdb.co/prom-design-doc

I'm also happy to discuss privately if you'd prefer - ajay (at) timescale.com.