Thanks for explaining.
Although the reason we use IaC so that we can manage all the changes via Code but you have a specific use-case.
I have never used Pulumi to create pagerduty, but I guess similar concept of state file applies to it.
Assuming you have other resources as part of the same stack which you still want to be managed by Pulumi
If I was you I would try to:
• Hack into the state file, remove any references for that resource from that stack,
• Create a new stack which only has that particular resource and import (the resource which was exported in the last step) as part of the stack. New stack wont have any other resources apart from the one which u imported.
As a result, you wont be updating the stack. So, in case even if you make changes via console, it wont effect the stack as you wont be updating it