Poe Lim wrote:

The worry I think is more on the GF choking on the gravel (I've only seen it
happen once, and the GF had this pebble stuck in its mouth for several
weeks, but was otherwise fine), hence anything that is smaller than the GF's
mouth should be fine. Mine seems happy with 2-3mm gravel.

I think I'm going to section a portion of my tank with large cobbles
that definitely won't fit in their mouth, a big rock, have some bare
bottom and have plants in a pot with sand and also my cave/bridge
from my current tank.