For the Nucleus, it doesn’t make sense (because you will hit other walls), but for the Nucleus+, it may be required if you have a very large library. We had a user that was coming close to 8GB used up with a bit short of 350k tracks.
We have another customer with 700k tracks that will blow past 16GB at some higher number (unknown what).
However, at libraries that large, you will have other performance issues that do not involve RAM.
Depends on the model. Best is to open it up and look. Then install. If you know computers, do it. Otherwise, take it to someone who does.