Not sure about turnkey solutions for finding vulnerabilities that doesn't involve having to hand over a bunch of identity proofs for them to store on their insecure infra and also enrolling in programs.

Besides that, hiring a beefy GPU instance at Vast.ai or similar places then running your own uncensored models on it, I've had great success with AEON-7/Qwen3.6-27B-AEON-Ultimate-Uncensored-NVFP4, smart + uncensored, but there are lots of options, probably some are already tailored for security research.