Hello Florian, I see several questions here 
Let’s proceed in order :
With the help of Robotmk you can run RF tests periodically on dedicated testnodes (Win/Linux) and integrate the tests into Checkmk.
From version 2.4 onwards, not only tests, but also any keywords can be covered and monitored at runtime.
I had actually never considered the integration of RemoteServer, which could ‘deliver’ libraries to test nodes.
…the use case sounds interesting, but I wonder what problem we could really solve with it.
Imho, a client-side installation cannot be completely dispensed with that approach, because even if pure Python libraries are loaded via remote lib/HTTP, this still requires a) an existing Python installation and b) in the case of the browser library a local installation of NodeJS.
Robotmk as of today can build isolated runtime environments under the hood for each suite to be executed - including Python, all libraries and NodeJS. (Currently with RCC, but the stack will be replaced as there is no longer a maintainer for RCC).
(Even the offline installation of environments on hosts without Internet is possible.)
This means: zero manual installation effort on the client side.
I am only explaining this in such detail so that the resulting added value is clear. How would RemoteServer fit into here?
It seems like it’s not possible to configure checks.
What do you mean with “checks”? Do you want to create rules, or discover services?
Is it possible to access check results via the API (already)?
With Livestatus you can query the monitoring core for the status data of hosts and services.
I know, not really a REST-like way but this should work ;-):
https://sgala.com/post/checkmk-api-get-service/
Best regards, Simon