Streaming to my Mac

I don't use a Firestick however I was able to find this "How To" article by using Google.

https://www.firesticktricks.com/cast-to-firestick.html

Mac's are computers, they are NOT TVs or external displays for other devices. Therefore, streaming from a Firestick to a Mac may not be possible. I would recommend contacting the developers of the Firestick and ask them to see if they support this functionality.

Is it the Fire Stick per se that's important?

Or some service on it that might also have a Web interface or a Mac application front end? E.g., if you want to view YouTube videos, it would be much easier to go to the YouTube Web site with Safari, than to feed the output of a Fire Stick into an external video capture device and then watch YouTube via the captured video stream.