you can do a lot with various anubias, mosses, ferns, and crypts. check the link in my signature to my betta barracks. everything there is low light, no CO2.
as for tank mates, there really isnt much you could do. you could put a nerite snail or two in. amano shrimp and RCS may get eaten, and would likely hide all the time anyway with a betta in the tank.
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