any other players with maxed out islands?

And other stuff like the golden tools

If maxed out is the total completion of all the NM Achievements which includes the critterpedia, all gold tools plus more, then yes I have maxed out more than once.

Nice how many?

I've maxed out once with all that @Lee has mentioned and completed catalog. My 2nd player just has 5 more kk concerts to do. But I'm not doing completing catalog again!!.. it was sooo hard :)

😉it is for sure !! :) it took me a while :)