tbh I tried sand for the first time in his tank and I don't like it at all. Thanks though I'll see about the dwarf sag
You can find them online or se if anyone near you is selling them
I second the anubias, especially since bettas love to lounge on the leaves. The betta can also hide under the leaves when he's sleeping.
Seems like you've got lots of answers about the plants, maybe you could add a background to cover up the cords behind the tank?
As the plants you have grow, they will hide what is behind them.
Have you considered a backdrop for the tank?
They aren't necessary, but give an added depth to the tank.
When I didn't see any I liked, I just cut a black trashbag and taped it to the back. It did the trick to make the plants and substrate pop.