There really isn't much choice of complete flatland bikes in 2020.
Over in Japan there are bikes from Ares, TNB and MotelWorks.
Then you have the Colony Apprentice, AUTUM STAY HUNGRY, KHE CHRIS BÖHM and that's about all I can think of.
Over in the US good luck finding any of these, except for ARES that FlatlandFuel carries.