what trickerie recommends is the best option for light. now since that makes it open-top, a betta is not a good choice.
the issue with tanks under 5 gal, is that most heaters dont keep the temp stable (they can keep the average at what you set it to, but because the body of water is so small, the fluctuations away from that are large. thats the main reason i dont recommend tanks that size for bettas, its very stressful for them in particular, as the temp needs to be higher than for most fish species (78-82 for regular maintenance).
i would ditch the top, get an azoo palm filter (they have em on drsfosterandsmith) or similar small HOB, and make it a neocardina shrimp tank. cover the intake with a filter sponge to keep shrimplets from being sucked in.
red cherrys are pretty tough to kill. i had 3 who hitchhiked as shrimplets into a betta tank, grew up, survived over 6 months with the betta, 2 treatements of copper sulfate for a velvet issue, and one was a female and even berried up during that period. 2 were moved when i finally caught them, and 1 is still in there (saw him 2 weeks ago).
for a low-light small tank, i would go with flourite. maybe add a very thin layer of MTS underneath, or just put root tabs near root feeding plants (like cryptocoryne species).
some plants to consider are mosses, pelia, c. parva, c. wendti, l. sessiliflora, anubias petite, m pteporus varieties (in the background), m. minuta, and lileopsis sp (in the background).
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