Typescript gets converted to javascript during the webpack process, the browser doesn’t natively parse typescript.
The plugins that are in core grafana are both in typescript and refer to paths in grafana source.
The best way to get started is to use something like this as a template: https://github.com/grafana/clock-panel
There is also a fork of singlestat here: https://github.com/black-mirror-1/singlestat-math
(that one does not use webpack though)
I’ve been wanting to create a “model” panel and datasource plugin for a while now to be used as starter, or a generator of some kind.