Bettas like to bite mystery snails.
Yes those sound like glowlight tetras. Not freaky Glo fish tetras.
I'd do either pygmy cories or Otos plus malaysian trumpet snails. I got Otos as a beginner, after the tank was up for a month. I buy them if they re in the store for a week first, and I drip acclimate. I'd make sure you understand GH, KH, and ph before getting Otos and your tank has been stable for quite awhile.
Malaysian trumpet snails are often free, are pretty interesting, and are amazing cleaners. They'll reproduce a lot but only to the point that the food supports. They don't contribute much bioload either, while mystery snails add so much poop they're not helpful.
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