On sale, €33 at Media Markt, I got a digital photo frame.
It has a slot for a USB stick, and for various memory cards. It looks like an upgraded version of one I bought for my parents a year ago, where the USB interface worked well but the card reader seemed unreliable. So I put one of the many free conference USB sticks in my collection in.
People seem to have an instinct to unplug these things continuously. Why? You don't put curtains over the print photos on your wall and only open the curtains for a few minutes at a time to look at the photos behind.
The frame is 16:9 aspect ratio. My camera makes files of ratio 4:3 (or 3:4 in landscape). (apparently print photos are usually 3:2. my camera has a helper mode that overlays grey bars on screen to show you 3:2 ratio. But it doesn't have a similar mode for 16:9)
On my laptop, I have gimp. But I found that Preview is good enough for rough cropping of photos to size. That's the technical side of cropping easily dealt with. On the artistic side, though, its hard to get in the habit of evaluating photos for such cropping - photos that I think of as "too much space at the top / bottom" are ones that are perfect for this frame, and photos that fill the frame nicely are too full for cropping.
As the frame is so low resolution (~ VGA) its possibly to crop smaller details from a frame, so that you end up with an entirely new picture rather than something that looks like the original photo but a bit cropped.
I've had a desire but not enough motivation to actually look at my photos from a cropping perspective. Perhaps this will provide the motivation.