Delve is not commonly used Nigerian English nor is it common in the corrupt form of English that is widely spoken in Nigeria called pidgin. The link you shared

Delve is not commonly used Nigerian English nor is it common in the corrupt form of English that is widely spoken in Nigeria called pidgin. The link you shared doesn’t really back up your claim though. It merely talks about government communications and reporting by the press that tend to use unfamiliar words when simple words would have done the same job. That’s a phenomenon that’s not unique to Nigerians though.