Greetings,
Based on my findings,
1. The consulate of Italy are in charge of Malta visa application in Nigeria
2. The consulate does that via online portal using the link (https://it.tlscontact.com/ng/splash.php)
3. The consulate issue only a short stay visa to applicant who has Malta as their destination.
4. Due to COVID-19 protocol, Countries within the African region that has malta embassy can not approve Long term visa to Non EU Registered Nurse as Nigeria is categorized on Malta's dark red country list.
5. Finally, there is a link (https://travelauthorisation.gov.mt/) provided for application for authorisation for exceptional travel to Malta from dark red countries/zones where there is a current Travel ban.
Note: This information is liable to changes at any point in time.