TRex is great, been using it for a while.

https://ameba.co/trex/ https://github.com/amebalabs/TRex/releases/tag/v2.0.0

How would you differentiate from how MacOS itself does this, without any need for third-party apps?

I haven’t found it to be much of an issue to select the text I want from the screenshot in Preview, QuickLook, Photos, etc.

Automatic copying seems like it would be of very limited use.

Aren't there a lot of these? Like a lot a lot?