You should be able to do so.
Grafana should have DT as a Source of information. If you guys don't want to use the Grafana Plugin, would need to create your own or search in GitHub if anyone did it. (Did a fast search and found this https://github.com/piotr1212/grafana-dynatrace-datasource)
Haven't test it.
The open-source plugin's only weakness is that it uses the v1 apis. I have been at this juncture myself. Grafana Enterprise wasn't an option - so decided to see how easy it was to write your own.
I built a plugin using the v2 API but not really any of its new transform features. So it did what a plugin using the v1 APi could do - but was much easier to implement. It took 2 days to prototype and about 2 weeks of tweaking. I was unsatisfied with a few aspects of it, and ultimately decided to just move on to other things.
I would say that writing your own would require strong development skills - especially problem solving and debugging - unless you are already familiar with Grafana's internal architecture.