Any idea on how to roll-your-own canary token for an unsupported token provider like Cloudflare/Stripe/OpenAI? Do you just make a real Cloudflare/Stripe/OpenAI account, create an API key, and vibecode an alerting system?

I'm kinda surprised that they haven't expanded beyond their existing token providers.

That's the issue. If the first-parties don't provide a means to mint canaries you have to mint your own real keys.