At Orb (https://www.withorb.com/) we’ve worked with a bunch of infra customers that are in a similar situation to what you’re describing. Generally, usage tracking and usage reporting is not the hard part. We think that giving you a full SQL layer on top of raw events is very powerful, so we provide direct SQL access to your events. Naturally, we use a real-time time series database under the hood to power that.

We’re working hard to make it easy to send data to us (e.g. just drop it in S3). Granted, this isn’t ideal per your note of already throwing it into VictoriaMetrics, but we’re finding that often times companies don’t have the optimized in-house infra to run the sort of usage metric queries to go from raw events -> invoice, especially when you get to >100k events/second scale. It often makes sense for us to control the storage (and sharding) format — and we can bring those costs down over time.

Given the usage events and the SQL queries over them, we then focus a bunch on making the core billing interactions work well, do invoice delivery for you (example: https://invoices.withorb.com/view?token=IlJwOVRSdWhEQ3NiRUVH...), and make it easy for you to do financial reporting & rev-rec (honestly, this is its own rabbithole — but we find it’s extremely outside the core competency of eng/product teams)