It's not a plugin available out of the box in GrandNode. If you want to have a developer support for third party plugins, you can always use it here.
All payment methods are available here: https://grandnode.com/payments
I implemented a little workaround.
I will investigate it, here is the work item.
So please give us steps how can we reproduce the issue.
You need to enter it, it's your creativity. If I remember well, it must have at least 16 chars.
Is this behaviour noticable also on our demo page? Or just in your environment? Can you share some statistics about it?
Yes, you can use it in Postman.
Examples can be found here (for example operations with products):
And you use generated token in Auth Type field.
You have to login to account that has admin access.
Did you get any error?