Wanted to provide an update here: we are planning improvements for our photos experience; but don’t have a timetable to share just yet about this particular ask.dbatl commented
You can sort and rearrange photos in a regular file folder, but not in a photo album. And even if you go ahead and rearrange your photos in a file folder and THEN create a photo album from that file folder, alas, all changes are lost. Beyond frustrating. Hard to understand how MS has not fixed this yet.