I know there are some forum questions about adding an external library but this one is not on CDN.
Question 1: Can I add this myself to a CDN somehow, and if so what file(s) do I need to add?
Question 2: if that's not possible, any other way to use the function?
Any help is appreciated, I tried adding some files with the add scripts and styles but it doesn't work.
At the moment, to use an external library in a Retool app it has to have a UMD build. There's some investigation into expanding which libraries can be used, including increasing the number of libraries supported in Workflows. For the time being, however, this may not be a supported library.
You may be able to build your own custom component using this guide as a way to use the module but the process is somewhat complex. Unfortunately, I'm not familiar enough with the library or its dependencies to give more specific recommendations but perhaps someone else is!