Tools to build Customer-Facing Analytics into our Product?

Hey,
I'm founding a SaaS startup and we're about to implement customer facing analytics, e.g. our B2B customers have a dashboard where they can view KPI's about the performance of our tool. So I'm looking for ways how to do it :)

For our current customers, we'll already track millions of events per month. Peak load would be around 1k simultaneous events, "worst case" around 5k.

I've found the following tools already

https://verbdata.com/
https://keen.io/
https://www.datadoghq.com/
https://aiven.io/
https://www.rilldata.com/
and some more which could useful to implement it..
Also found this thread (already 2 years old)

I'm not really happy with any of these: Some require me to write own models, some need an external data source (eg. I need to create a database first with a different tool), some are targeted to enterprise businesses, some have other limits which make it harder to use our data. All are too expensive for our use case, except Rill which looks most interesting, but is kinda overkill.

I'm looking for a tool where I make 1 request to track an event, and 1 request in our dashboards to get data that I can plot on a chart. Especially for quickly testing how new metrics help our customers we need a flexible solution.

So I have two questions:

1: Does anyone know a tool that might be interesting for us? Would prefer focusing on our core product and use an existing tool instead of building kind of a side product.
2: In case there is no such solution: Is anyone else interested in a solution that can be used for custom internal and customer facing analytics? Because I know how to build what I want and I'll just build it if I don't find something that fits.