this might be a stupid question, but could someone please tell me if reicast is available yet on the google play version of retroarch, and if so where is it?
no, the libretro version isn’t packaged for android yet. You should use standalone for now.
Patiently waiting for it though 
If you are on AndroidTV, you’ll need a mouse to config the input.
Also waiting for Reicast core because the devs of standalone Reicast refuse to add analog mapping even though I explained my plight with difficult touchscreen controls in the Sonic Adventure games (frequent deaths in City Escape’s bottomless pits from aiming difficulty) and the obviously fast paced gameplay. Even having it read a controller’s analog stick didn’t work properly at first.
I used a keyboard to run the NullDC (predecessor) in the early days and it has analog mapping which let me move around and play rather well to the limits of keyboard inputs. Having the Reicast core would allow me to actually move via keys pre-mapped for the analog stick,in my case I,K,J,L on Android for N64 because of keyboard ghosting limits,I can’t use a controller for unfair personal reasons.