Skills do something you could already do with folder level readme files and hyperlinks inside source, but in a vendor-locked-in way. Not a fan.
It's definitely not vendor locked. For instance, I have made it work with Gemini with Open-Skills[1].
It is after all a collection of instructions and code that any other llm can read and understand and then do a code execution (via tool call / mcp call)
1. Open-Skills: https://github.com/BandarLabs/open-skills
They are just text files though. I'm sensitive to vendor lock-in and do not perceive a standard folder structure and bare text files to be that.