My single biggest frustration with excessive use of outdoor illumination at night is that it means I have to use blackout curtains to have a dark bedroom at night.
Without that, there would be absolutely no reason to even think about a technological solution for waking up with the sun.
There are expensive ones that do a really good job of blocking light, and inexpensive ones that let some light through.
Walmart's house brand, Mainstays, is the later. They block a decent amount of light, but some will get through.
I found that if you use blackout curtains with grommets, like the Mainstays [1], you can simply double them up. Set one panel on top of another with their grommets aligned, and you have a double blackout curtain. A pair of $10 Mainstay panels doubled work as well as the expensive ones which are way more than 2x$10 per panel.
If you need more than one panel (or pairs of doubled panels) side by side to cover your window, the grommets can help there too. Overlap them side by side by a couple grommets. You've now got effectively one wider panel.
I once jury-rigged blackout curtains by attempting to dye regular white curtains with a navy dye; the colour only partially took, and turned out to be at precisely the right spot on the em spectrum to act as an irresistible magnet for bees, which would consistently wake me on summer mornings coming though the open window and buzzing against the botched curtains, rather obviating the purpose!
In my case my blackout curtains are not to help with sleep. They are in my living room, where the only good spot for my TV is opposite a window that can get a lot of sunlight.
When watching TV the bright reflections in the screen from that window can be quite annoying, especially during darker scenes. During parts of some days you can actually see a reflection of the sun itself in the TV screen, making it hard to see even bright scenes.
We live fairly rural so it's not a huge issue. The moon is usually the brightest thing we have to deal with. I have considered automated black out blinds even for that (plus for daytime movie viewing and naps!)
Without that, there would be absolutely no reason to even think about a technological solution for waking up with the sun.