thanks to @stefan.hoehn for the flowers 
.
I’m not an expert in that topic, but I was able to use e.g. the pie chart for eChart directly - but you have to process the data most likely in a rule to have a format than can be used. I did not use other chart types yet - but it seems to work to a degree in 4.1.1. The only problem I’ve encountered is that I could not define callback functions in the UI to perform more advanced formatting …
Have a look at Create a pie chart with oh-chart to show top 5 processes (system information) - that’s the chart I’ve done so far.
Let me know if it helped - and if it worked maybe also document what was the things that need to be considered.
I do not know if this will prevent e.g. pie chart to work in the future - we’ll see - maybe there’ll be a way to keep the bundle size reasonable and keep the functionality (e.g. lazy loading of modules in case they are used …).
If it works maybe you have time to check if it still works with the snapshot including the updates. At the moment I’m very busy & do not have time - but if you do not know how to do this I’ll add it to my todo list 
let me know.
Btw.: For such experiments with other openHAB version a docker container can be very useful to isolate the test system from your productive environment.
with kind regards,
Patrik