Maybe laetacara? Laetacara curviceps – Dwarf Flag Cichlid (Acara curviceps, Aequidens curviceps) — Seriously Fish
other laetacaras are pretty too Species Snapshot: Laetacara araguaiae, the Araguaia dwarf acara - AMAZONAS Magazine
& Laetacara dorsigera – Redbreast Acara (Acara dorsiger, Aequidens dorsiger) — Seriously Fish
I've never kept them but always thought they were cute.
Of course there are many apistogramma species but may be too small? I've kept a few species. I like that males look very different from the usually mostly yellow females. A pretty contrast but with compatibilty & breeding possiblities.
Any cichlids might dig, corys too. You may want to let the plants get well rooted or put some smaller stones around the plant bases. Give them a cave or 2 with a smooth rock to lay eggs on. Keep plants away from the entrance. Corys will not understand the cichlid territory issues & will eat eggs or small fry if they can. But that might be ok unless you want more than a couple accidental survivors. The cichlids will try to defend the chosen cave but probably can't hurt the catfish. The thing with cichlids is they breed every month or more so losing most to corys or ready to breed again parents so it might work out better that way.
You know you can start with plants before your tank is cycled. They often have some of the beneficial bacteria on their surfaces. I'm not sure hydroponically grown 1s do but the don't have snails either
I think you may have missed my update on ammonia dosing in your other thread, I think 1/4 cup may be too much, start with a tablespoon or 2 & test! Plants love ammonia, but not much over 1 or 2 ppm at most. They can get "burned".
What cory species are you thinking of? Pygmaeus are almost not bottom fish & tiny, they don't dig as I recall. Will you have tetras or other mid-upper water fish? Your name makes me think you might