Further to this, I was able to disable the inclusion of the portal script from unpkg by manually commenting out the following line of code (181) in my installation:
Doesn’t seem to have caused major adverse effects so far (I have only done a cursory smoke test) - of course this is only a manual workaround and not ideal because I can’t automatically update my deployment without this patch.
But it might help those who want to temporarily disable this until the feature flag idea is reviewed by the team and possibly taken into consideration.