I have CPDs and they are small,colorful, active and show no sign of being jumpers.
I wish I had more info chili and other micro rasboras. I like them.
If Gertrudes are anything like Furcata forktail rainbows, I find them to be sensitive to excessive CO2
. I killed off a school last year after making a bad adjustment to the bubble count. They are IMO
on the larger side for nano fish. They have this shimmy when they swim reminiscent of a molly in distress, if that makes any sense.
I have no experience with clown killies.
Ember tetras are another nano fish to check out.
You could continue the nano theme with a school of pygmy cories.