Would someone who generated a seed but never had any btc sent to their wallet even count as an active address?
What do you count as "active" addresses?
As o_e_l_e_o said, there is no way of knowing which addresses have been generated but never used. In other words, there is no difference between a "generated" address and an "ungenerated" address. They are all equally valid. The only information we can find out is whether the address was ever used in a blockchain transaction, i.e., whether it was ever used as an output address.
Keep in mind that you can generate an address even offline. And, a long time ago I even saw instructions on how to generate a valid Bitcoin address manually, by hand.