Zoro emulating a Samurai of Wano has been a plotpoint all throughout the arc. It's more apparent with him compared to any other Strawhat or Alliance pirate who's assumed identities and roles were less discerned.
Zoro is remarked as a Samurai in front of the magistrate and told to commit Seppuku like a true Samurai, something Zoro was willing to do until he smelled blood on the magistrate.
Luffy, his close friend, mistook him for a Wano native Samurai upon their reunion.
Toko and Hiyori assume him to be a Wano Samurai.
Upon learning who he is, still notes his resemblance to Wano's Samurai.
Kawamatsu, a Samurai himself, referred to Zoro as one from first meet.
Once more, all the pirates took on assumed identities and roles, but none have been as exploited as Zoro's. These moments I highlighted span chapters 909 to 952. Long after every other Strawhat shed their identities and simply went into hiding. Meanwhile, Zoro hasn't stopped being addressed as "Samurai" or "Ronin" until the end of Act 2, and he hadn't stopped his wandering like a Ronin until then as well. Speaking of "Ronin", the number of times and the number of characters who address him as so was so numerous, I didn't bother going through it all.
In fact, it's outright confirmed that Zoro's background links him to Wano and Samurai in general. Even if he isn't blood tied, he has been trained and brought up by a former Wano swordsmith and his son, both hailing from the Shimotsuki clan, said to once house the greatest Samurai of Wano.
He also practices and adheres to the code of Bushido. Especially in Wano where we've seen it in full, but that's a matter for another day. Though I do think it should be noted that the one arc where Zoro cares about the locals most happens to be Wano, like he is a warrior of that land and seeks to protect it like all Samurai do.
In conclusion, sure, you can be pedantic about Zoro technically not being a Samurai, but it's asking a lot to ignore all Oda has done to link him to them, both directly and indirectly.