it's not your own if you pass it onto an LLM

then it's just LLM writings prompted by you

how do I know which part is made up by the LLM or it's own interpretation or it's own opinion etc?

how can there be any value if I have to scrutinize every single word and decide whether it's truly what you intended to write or if it's mangling things, or if it's all just made up for engagement?

I've made this exact argument to other people, so I fully understand what you're saying here and agree with it.

I use the model in the same way a non-native writer would, for clarity. So it's critically important to me that there is no model interpretation or opinion added to my own.

I agree that whether it still counts as "my own" is up for debate. Made more complicated by the fact that I'm mostly using voice-to-text these days, so I'm dictating more than writing.