anything med-high light isnt best for beginners. more money and time put into it than should be in case the person decides not to go that route.
-driftwood with some java fern tied to it (use fishing line, but make sure to not leave any strands out cause fish can get caught up in it and die)
-look up java moss wall
their beautiful once they grow in, but mind the moss grows suuuper slow, but i am sure someone on the forum could send you some.
-anacharis is an easy plant and to make more you break off the top of a healthy plant and plant it and itll root
-wentiis are low-med light but they have red tinted ones and green, to add some color.
-anubis has large leaves for the betta to hide under if nervous
rocks and driftwood are great additions to make a tank look natural, and you can mix live with fake plants. the java moss will be great for any fry born to hide in, btw, leaves more of a chance for them to survive.
then you could find some larger river stones (like half palm sized ones that are natural colored) to add some variation of shapes to the tank as well
i would not use bamboo...i dk if its 100% aquatic.. you have to have most the stalk out of water and idk if the bottom rots off
any driftwood you use from outside (make sure its driftwood first and not some rotting wood. go to lake or river.) you need to boil it really good before putting it in tank to kill off anything maybe growin up on it.