The cotnetn rules and thus JS unsafe-inline is mentioned as not allowed here
as unsafe-inline is not in the default CSP for Script-src
And noted in the Google Analytics docs
Since Twitch extensions do not allow inline Javascript
it’s also inferred via 2.8
2.8 All front-end HTML, CSS, and Javascript files used by your Extension must be included in the zip file for your assets. You should not include extraneous files or code not used by your extension.
The restrictions on content, probably, could be more explicit however.