Best way to migrate off ChatGPT when most of my work lives in long threads?

I’m considering moving some workflows off OpenAI/ChatGPT due to recent reporting around OpenAI and the DOW. I’m mostly trying to reduce vendor lock-in and make my workflows portable.

My challenge: most of my work lives inside ChatGPT threads (long-running project conversations + reusable prompts). I know exporting ChatGPT gives me an archive, but I’m not sure how people turn that into something usable on another LLM platform.

For anyone who’s made the switch:

•	What did you migrate vs rebuild?

•	How did you handle long threads (summarize into docs, convert to a knowledge base, scripts/tools)?

•	Any recommended pattern for provider-neutral prompt templates?

•	Biggest gotchas (formatting/JSON, tool calling, attachments, RAG/embeddings, compliance/security)?

Not looking to debate politics — just practical advice and lessons learned.