Without being very familiar with any of them, I suspect Low German and Dutch are pretty closely related?

They blend into each other. https://en.wikipedia.org/wiki/Rhenish_fan -- https://duckduckgo.com/?q=german+dutch+isoglosses&iar=images

Very close, and I can confirm that as someone who knows "standard Dutch" it is fairly easy to read.

It wouldn't surprise me if it is even easier for someone from the german-dutch border region who is fluent in a local dialect.