Non Profit Theme or Plugins

I was wondering if anyone here on the support forum has had any experience creating a nonprofit CMS. It’s been many years since I’ve played with WordPress and I’m overwhelmed/perplexed by the number of theme choices.

Are there websites available that display the themes according to purpose?

If I’m looking for plug-ins, Are there certain widgets or whatnot that I should be looking for a nonprofit?

Any advice or direction is greatly appreciated in advance.

Many thanks.