Assuming you haven’t purchased the tank yet, (and have the space) why not go a bit larger? Just to allow yourself more options.
I don’t think I’ve ever regretted going bigger on buying a tank.
But anyway; various tetras, some barbs, dwarf gourami, cories, etc. could all work. My kids are totally into yoyo loaches, like cories they frolick and are always moving and skimming surfaces and plants. I think kept in a sufficient number (5-6 or more) you’d likely be overstocked in that size tank though, depending also on its dimensions.