I do not know any online malls accepting bitcoin in Nigeria, are there malls that are very known like Jumia or Konga or where people meet like Jiji that people can buy things in bitcoin directly instead of paying naira?
Most online payments in Nigeria that I have seen that actually accept Bitcoin usually for in one of these two categories the very first category is those of small vendors that actually accepts crypto like stable coins and most especially bitcoin usually phone and gadget vendors.
Second is usually international payments that are also available in Nigeria so probably things like brokers bigger online marts that are not only available in Nigeria.