Is it possible to have a selected area and crop to selected pixels?
Sorry, but that is a terrible idea. Not cropping to selection, but destructive cropping which is what it would mean. One of the best things about Photo is a non-destructive workflow, including cropping (normally) which is like having the undo facility. Why would anyone want to change that ? Personally, I would recommend Photo to anybody because it does not throw stuff away. Surely it is better to embrace new improved methods, especially if they could prevent making mistakes. And what is the difference between crop to selection and a normal crop ?
What you want is simple and easy to do in Photo and without losing all the data. Although you can still delete the data easily enough afterwards if you want to but as a two step process, which at least makes you think before deleting.
If you prefer to work in a destructive way that cant be undone, fine. You need a program with a Destructive workflow. Try Photoshop, a destructive cropping process and only ten times the price.
Surely better to stick with Photo though and adapt to a non-destructive workflow though? Personally, I much prefer the Photo non-destructive cropping. If you really feel you still need it, you could put in a feature request.
If you need, it is easy enough to make a crop. Just crop the document as normal, press the C key and draw a crop box, that's it. No need to even make a selection first. Admittedly, the information is still there, Photo is persistent in trying to save you from yourself, so go Document > Flatten and it's all gone for good.
Here are two very easy non-destructive.methods that crop to a selection and still keep the original information
Make a selection first, press Ctrl + J. That copies the selection, and only the selection, to a new layer. copy it, (Ctr + C) then go File > New From Clipboard. It makes a new document exactly to the selection Plus, the original information is kept in the original file for safety.
Alternatively, draw a Rectangle above the the image, right click on the rectangle layer and go Mask to Below. Just the "selection".will be in it. Copy the layer Ctr + C and then go File > New From Clipboard again.
Ctrl + C then File > New From Clipboard is a two stage presses, and the original data is still there.(just in case) which has to be a good thing for safety, right ?. File > New From Clipboard.even has a keyboard shortcut or you can easily set your own.