I would honestly be fine with destroying the whole stack but that can't be done because I can't get past this error.

You can

pulumi stack run -f

to remove the stack and abandon all resources that were under management. You are then responsible for manually cleaning up anything that wasn’t already deleted.

As you say, that doesn't delete the hundreds of resources created though.

Yeah - I think what you really want here is the feature discussed in https://github.com/pulumi/pulumi/issues/3304.

Yep