The issue with there being a Ryuma parallel at this point in the game is that the buildup is simply not there. Not like it has been for Oden. Oden has been the central focus of the arc as "The Samurai that is to be surpassed." Outside of Gyukimaru during their fight, there hasn't really been a single person in the entirety of Wano whose even mentioned Ryuma, or even gone into any kind of detail about the man. We've gotten no Flashback on the guy, and very bare minimum information on his accomplishments. Oda even took Shusui away from Zoro, and gave him Enma instead. Everything has been about Oden. So Oda is really going to have to do something to bring drawing a parallel between Zoro and Ryuma in the eyes of the people of Wano to the forefront, because it's all been about Oden so far.
Oda doesn’t need to do anymore than he already has done. The Zoro-Ryuma parallel existed before we even got to the timeskip, never mind knowing about Oden. It didn’t need any focus because it’s been a slow burner that we’ve known about for years.
We had two Wano natives, Kine’mon and Gyukimaru, trying to take Shusui from Zoro because of what it meant to them. Zoro has Enma becayse he swapped it for Shusui. We know that when the fight is over, Zoro wants Hiyori to take him to Ryuma‘s grave. There’s Zoro being from Shimotsuki, which Oda basically told us in a SBS is going to come up as plot point. And Oda decided to specifically bring up the dragon killing legend with Gyukimaru, giving us the exact location it happened, which just so happened to be where the grand finale of the arc is going to happen.
Nothing more needs to be done to set up the parallel. Dragon Kaido above the FC, citizens running about in a panic, Zoro cuts him down and they all think “god, it’s like the stories of Ryuma”, with Gyukimaru seeing it and changing his earlier opinion of Zoro, that he was nothing more than a greedy little boy.