I like the choses you made on the radiata lion, either eels are great beginner eels, and bluejaw trigger.
For other options there are:
Small angels(lemonpeel, poters, coral beauty, etc.)
Tangs(yellow, purple, sailfin, kole, etc.)
Butterflys
Maroon Clowns(The only clown I would do because they get big and aggressive and is the only smaller fish you can get with a lion)
Hawkfish(Longenose is an example but there are a lot more)
Rabbitfish(foxface)
and the list goes on but I can't think of any others.
I would do a small angel, tang, maroon clowns, and a rabbit fish.