I wouldn't say meet in person, because you are not "in person". I would say: "It's nice to finally meet you!" "It's nice to finally see you!"

in person won't be correct in this scenario as you are not in a physical meeting with the person.

As you're meeting the person virtually, it'll be better to say "it's nice to finally meet you"

You'd only use that when you literally meet them in person, as in physically. You are next to each other in the real world. You could say "it's nice to finally see you", or even "it's nice to finally actually meet you", but just not in person. "In person" is just for when they are physically present. By the way, your profile says you speak Cantonese. I only looked because I know someone from Shenzhen who goes by the name of Cassie. I'm about to move to Shenzhen to teach English. I'm currently focusing on Mandarin but I'd like to learn Cantonese at some point, too. If you'd be interested in a language exchange, let me know!