macOS GUI software to find and replace?

I second BBEdit. I have used BBEdit since the late 90s and I personally find it to have the best Search and Replace GUI of any editor I have used on any platform. This despite the fact, I mostly use VSCode on Windows for the last few years

The GUI is very keyboard friendly

It supports GREP

It remembers past searches and replaces so when you need to repeat a search from earlier you don’t have to reconstruct it

Text Factories allow you to build very complex work flows

The presentation of search results is first rate.

Multi-file search GUI and results presentation is the best.

Oh, and the file comparison tools are amount the best too.

Yes, it's called BBEdit.