To answer your original question about recommended plants for that light set up and would be pretty.
A marimo moss ball, every 2 weeks just take it out of the tank, squeeze it and roll it back into a ball.
Java Moss is little to no maint, it just grows like crazy.
Java Fern you can tie to a rock and it will grow slowly, don't bury the rhizome.
Float some water sprite, the betta will sleep/hang out on it
Water Wisteria grows fast but might be to big for that tank. Would be fin so long as you prune it.
Bettas love densely planted tanks, they hide and swim through all the spots exploring.
I'm sure there are more than this, these are just the super easy ones to take care of.
Also Indian Almond leaves are great to float in the tank, they will climb up on them and it will turn the water a tea color (if you like that).
All my bettas have a Betta Leaf suction cupped to the side of their tanks, made by Zoo Med, every single one of them loves it and uses it daily.