It's easy to forget what files contain what from name alone especially when returning to them after a long time. Showing previews for .pyxel files on the open dialogue would be excellent.
+1 to this. I work with Pyxel a lot and my work folder has many many pyxel files. Proper naming can only do so much. Being able to quickly see the contents of each file in a thumbnail style would be great. Not sure how feasible this is because even photoshop files don't do this natively in windows, but if you could at least see the thumbnails for pyxel files in a folder from within a function in pyxel that'd be good enough.
Hmm, maybe a simple solution would be for Pyxel Edit to store snapshots for recently opened documents, and show thumbnails for them in a list on startup or through a "Open recent..." menu option. If the file was modified externally the thumbnail wouldn't be correct though. A more complex solution would be to store thumbnails in the file format somehow.