Trying to add simple dropdown <div> into first table cell when table is first created (vanilla js)

[peppies]

[etrepum]

You can't put unmanaged DOM children inside of lexical managed elements with the current public APIs. Generally speaking this sort of UI is currently implemented by adding DOM outside of the editor and positioning it in the right place relative to the node.

There is an undocumented internal DOMSlot API that could be used to do this in theory but you will have to read the code to understand how it works, and you're on your own since it's not currently a documented and supported API that and it may change in the future.